So I know there are a handful of Bionic/rezound threads out there, but none of them really quite....cover it. It's mostly just "yeah I like it" or "these specs are better than these specs." You have to dig to maybe find a post or two that really says something that will influence your decision and allow you to know what you'll be getting yourself into. With a few pictures scattered throughough, I've made a list since I've received my Rezound, adding to it everytime I noticed a little detail that either made my experience easier or more frustrating. Each has pro's and con's in many ways other than specs, and I'm here to try and cover some of those. If anyone wants to add anything, I will gladly update this post to reflect it. So, let's begin...
First, let's get a few things out of the way: Yes, we all know the Rezound can be unlocked and has more dev support. The theories on updates however are outdated in my opinion. HTC is no longer terrible about updates and Motorola is. Sort of. I feel the Bionic is the exception because it was such a 4g beta phone. So I believe they didn't release an update for months because they didn't know what to do. They weren't over there laughing behind our backs with money bag hats, they just couldn't figure it out. Simple as that. Forget the network growing pains, the Bionic had other issues that took too long to address. Also stop complaining about the Bionic not having any dev support...that's not happening. Sure the Rezound will have more, but the Bionic still has several ROMS, including ICS, which are updated regularly and the devs are always available for support. Unless you yourself are a dev, don't worry about this.
Biggest difference - Data connectivity. You heard correct, it's almost non-existant on the Rezound. Sad, but true. However most people who will read this already know this much, so if you never had any problems but are just curious, then come on in!
We'll start with screen quality. This ultimately comes down to preference, but not necessarily based on looks alone; though, there is no one that's better than the other. Each screen was on full brightness as well as auto. First I'll cover the Rezound: Bright and beautiful. The clarity is unrivaled. However, sometimes it can be a bit overwhelming. You can tell it's LCD is "super," as it's a very "in your face" type of screen. I think the best way to compare differences is comparing the notification bar. The Rezound's is simply clearer. That's not to say the Bionic screen is muddled in any way, but it's the little differences in lighting. The Bionic just seems a bit darker. However, the biggest downfall is the light up buttons on the bottom. They can actually refer into the screen. It's really only noticeable on black areas, but I always read kindle at night with the lights off and I preferred the black background on my Bionic. It was straight up black. However on the Rezound, near the bottom of the screen, there's actually 4 white "glows" that go upward and fade away about 1-2 cm's in. Again it's only noticeable on black surfaces, but if you use the black background kindle, it's something you definitely have to get used to. To transition we'll discuss glare. Wow does the Bionic win hand's down. It's not just outside, it's over all glare. Lights above you, shadows, tilting it side to side, viewing it from an angle, everything, the Bionic is vastly superior. This is something I tested the most, and I'm telling you, the Bionic's pentile screen has taken care of the glare issue. The Rezound needs some work. Also even though they are both "4.3" inches, the Rezound screen seems just a incy-weency tiny bit smaller thanks to the borders. I don't have as much leniency with Swype when hitting a key on the edge, I actually have to stop before I get there or else my long fingers will just barely slip off and cut off the word. Incredibly frustrating. However, there is no denying the "screen door' effect of the pentile. Though, again, it's mostly only noticeable in the notification bar, particularly over the battery symbol, but if you sit there and look for it, you will notice it. If you can get used to viewing the screen as a whole it's a non-existant issue. But it's not like the Rezound which is off the bat clarity.
A useful post below from Jntdroid, though it easier to just quote it, thanks again.
Next up, speaker quality. In all honesty...the difference is slight. I really went through and listened to several songs on each, and believe it or not, but it seems like the Bionic speaker is a little more....structured. The Rezound speaker seems to be louder, but it also seems more muddled, the Bionic speaker, though not MUCH quieter, just had a slight advantage in clarity. Emphasis on slight. Even with the beats audio on and different settings in Poweramp for each. Most people use headphones anyways, and the difference is minor, though the Rezound seems to have more of a static-y sound in quiet moments, but nothing you won't hear on other mp3 players.
Advantage - Bionic, though not by enough to where it should really influence your decision.
Camera quality. Personally, I think when it comes down to it, the quality is identical. HOWEVER, there is a learning curve with the Bionic. You HAVE TO learn how to use the focus feature. And it's weird. You can't put the little square on what you want to focus on, usually you want it a little above. With the Rezound it's point and shoot, but the Bionic doesn't lose out completely, you just have to know how to use it. I tried this on two different Bionics and my replacement Rezound, and the quality difference when done correctly is almost none. Both cameras create beautiful outdoor shots and decent indoor, just gotta know how to use it.
Advantage - Rezound, not for quality, but for the ease of use.
Another interesting comparison I did was boot time. Put simply, if you did a battery pull on both, and started them at the exact same time, they are more or less completely even, with maybe a second or two advantage to the Bionic. However, the Rezound has the fastboot ability, meaning it takes about 5-10 seconds to restart. It's not as effective as a full battery pull, but it will still speed the phone up a bit if its memory becomes a little clogged. I like it, though it also seems to have caused certain issues with certain phones, but I wouldn't say it's a widespread issue. However the Bionic does not have a fastboot option, so every time you need to restart you have to wait that 3-4 minute period (give or take, depending on apps, launcher etc). Also to access recovery on the Rezound you have to do a battery pull. This isn't a bad thing, but you do have to remember to do it or else you'll start your phone normally. However, if you didn't, it'll be a fastboot, meaning it'll be ready to take out in about 5-10 seconds. No biggie.
Advantage - Rezound, unless you don't like the idea of fastboot or having to do a battery pull (you can do it while the phone is off and it will still let you into the dev menus).
Next up, charge time. Not a huge difference, though the Rezound does seem to go from about 20% to full on the extended battery about 30 minutes faster than the Bionic. I would've tested regular, but they only sent me an extended for my Rezound. I think the results would be similar, with the Rezound reaching 100% only slightly sooner than the Bionic. If you're like me and charge your phone at night when you're asleep, it doesn't matter; but, if you're always on the go and charging throughout the day, you'll probably notice the difference. Thus...
Advantage - Rezound, but again not by a huge margin.
Weight. This is an interesting concept because it varies a good bit depending on battery/case. Straight up no battery in either, the Rezound is a bit lighter. With the extended battery, I'd say it's close enough to not be mentioned, however with the diztronic soft case, the Bionic just seems thicker, and thus has a feeling of weight. It's hard to tell if it really is heavier, but IMO the brick like shape seemed to make it feel bigger. But I also wouldn't make a decision based on this, as when it comes down to it, not even looking at specs, the difference will be miniscule.
Advantage - Tie.
Now to games/apps. Another interesting concept that is bound to change over time. But at this point, the Bionic seems to be more compatible with more apps, particularly games. Even though the HTC can be unlocked and has tons of dev support (which may be the cause, don't know enough about development fancy pants stuff). And it's not like you're SOL with apps, like I said it's mostly games, but I have several games I bought on my Bionic that don't even show up on the Rezound in the market, mostly Gameloft games like MC3, or have screen cut off (which can go back to the Rezound screen being just a tiny bit smaller). Not a huge deal, but if you love to have every game available, just know the Rezound is still working on that.
Advantage - Bionic, though surely not for long.
Size. I'll let the pictures speak for themselves...the first 2 are extended battery with the available case and the 3rd is ext battery without a case, due to file upload limit I'll have to post the standard battery pictures and one more extended in a new post, so see below. All pictures were taken with a Bionic, and you'll notice how some of the pictures, though shot at almost an identical angle and the same set up, have a major difference in quality. Like I said, it's special and has to actually be set up.
And now for the obvious differences. HDMI - The Rezound does not have a mini HDMI plug in on the phone. You have to purchase an adapter to use the HDMI feature. The Bionic is simple plug and play. Also the Bionic has Webtop support, which, though only used by 1/10000000 people, is actually really cool. I was only able to dabble in it, but I thought it was awesome and am very disappointed this feature did not get more recognition. When it comes to docks, the Bionic is slightly more limited by choice/case/battery etc, but the Rezound isn't perfect either. Don't know as much about accessories though so anyone else feel free to chime in.
The Rezound's power button is on the right, audio jack on the left. This is reversed on the Bionic. Just pointing it out. Personally I prefer it as it is on the Rezound, but meh, no biggie. And of course the hump on the back of the Rezound. You love it or you hate it or you don't notice. With the extended battery you'll notice. I've heard several jokes at work about the jetpack on my phone from the ext battery, whereas I never heard a single comment about my Bionic WITH the case on it. Also just pointing it out. I'm not even going to mention blur or sense, as these are a thing of the past. With all the launchers and customization options out there, you can have whichever you want, or neither. Do not take this into account, as they both have their own bloat, which can be removed on both, and can be easily changed. Though the stock Sense 3.0 lock screen is way cooler than blur's. But just download widget locker and you're set on that one too.
Lastly, the inside under the back cover of the Rezound looks way cooler. A sort of see through red plastic. Nothing important, but I think it's cool to be able to look into the guts of the phone.
And alas, my list has come to an end. I feel like I'm missing something but I can't think of anything else right now. Hopefully this has helped somebody, it was mostly made for Google search purposes as I'm sure it'll fade away in the forums. Like I said, what was out there was just opinions and specs, nothing too in-depth. Might even be a little late, but I know people are still switching over to Rezound, so I just wanted to shed some light on what to expect. Any questions, feel free to ask. Again, see below for the last few pictures. Thanks guys
Edit: Thought of another difference. Just something I noticed. But the Bionic is MUCH easier to root than the Rezound. Mostly because you HAVE to unlock it before you can root it. So you kill two birds with one stone, but I was spoiled with all that one click goodness and it took me, a smartphone dev noob, a good bit of time to figure it all out without screwing anything up; my Bionic was rooted in like 3 minutes.
Edit: Some more information and perspectives!
Rezound / Razr / Bionic - Side by Side Pics and Videos