OK, mystery solved...now I understand the confusion. At least with iPhones, you must first Jailbreak the phone, so that you can then install and run an unsigned application that would otherwise be prevented from running.
Once the phone is Jailbroken, the unsigned app - the carrier unlocker is then installed and run, completing the carrier unlocking process.
Where it differs with Android phones is that from what I know, you don't need to Jailbreak them to install and run unsigned software that will unlock them from the carrier. To install unsigned software, or at least software not on the Play Store, you simply have to check a box in the Settings , Security & Screen Lock menu to "Allow installation of apps from unknown sources". So the term Jailbreak is synonymous with carrier unlocking when referring to at least iPhones. The same is apparently not true for Android phones.
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