Sprint with WiMax is using a higer frequency than Verizon's LTE. The lower frequencies penetrate structures better. Ultimately your distance from each carrier's tower will be a factor but if the distances are the same the building penetration by LTE should be better.
i took a video to test that. i made a bs video that was like 60 something mbs and uploaded it to mediafire and it took about 3 or 4 seconds. amazing.If you read the review from Engadget, they say the speed test results are not accurate:
[Update: We've been told by Ookla that the Thunderbolt's massive send buffer is responsible for the erroneously high uplink speeds -- they've got a fix in the works and it'll be available as an update to the Speedtest.net app soon.]
HTC Thunderbolt review -- Engadget