Here's a list of advantages/disadvantages the Thunderbolt has over the Bionic:
Thunderbolt has more RAM: 756 compared to Bionic's 512.
Thunderbolt has a Kickstand - and contrary to popular belief, you CAN charge it while using it, because the Kickstand also lets you stand the phone upright.
Thunderbolt has a 32GB microSD card pre-installed, Bionic doesn't have one.
Thunderbolt can handle data and voice over 3G/4G, Bionic can't
Thunderbolt has a built-in FM radio (Not sure if there's an app for this, but hey).
Thunderbolt has an external speaker; Bionic doesn't.
Thunderbolt has DLNA connectivity, Bionic doesn't (to my knowledge)
RUMORS:
Thunderbolt will have an unlocked bootloader, Bionic will almost certainly have a locked one
Thunderbolt will have a device that allows connecting to non-DLNA enabled TV's, while the Bionic can only be connected to HDMI-enabled TV's.
DROID BIONIC Advantages over Thunderbolt:
Dual-Core Tegra 2 Processor, both clocked at 1GHz (Although according to this video: YouTube - HTC Thunderbolt Unboxing and Demonstration , the Thunderbolt is still faster).
DDR2 RAM instead of regular (I think DDR2 RAM reads/writes faster).
More built-in memory (16GB's compared to the Thunderbolt's 8GB's, although the BIONIC doesn't have a microSD pre-installed, so the Thunderbolt will still have more memory out of the box at 40GBs).
This is still speculation on the Bionic end. No real specs have been released yet.. The phone is not finished yet. 512MB DDR2 Ram is faster then 756MB Ram. I have not heard that the Thunderbolt being DDR2. Motorola always comes with Micro SD Card installed so we just have to wait and see will it be 16G or 32G if it comes with 32G Micro SD then that is 48Gs the Bionic will have. Yes the front facing Camera is better then the Bionic's. But really how many of us is going to use it all the time. especially if your friends do not have the front facing camera.. All I am saying is wait until Motorola releases the full specs before speculating. I am one who do not care if my phone is locked or not.. I do not root my phones
I wanted to clear a few of these things up:
RAM - TB has more RAM (regular, not DDR2), while Bionic has better RAM (DDR2, reads/writes twice as fast as regular). It remains to be seen who will come out on top on that issue (space vs. speed).
FFC - Bolt is clear winner here, Bionic will have blurry video-chat, but how many people will really use it very often? And it won't even matter at all if you don't know anyone else with a FFC phone yet.
Kickstand - sure you can charge while video-chatting, but what about while watching a video? Nope. I guess HTC somehow thought video chat functionality was more important than watching videos/movies.
MicroSD card - the X came with a 16gig, so I imagine the Bionic will too. Still, that leaves the TB with 40 gig out of the box and the Bionic with 32.
Simultaneous talk/data - this feature will be possible on the TB, but not a selling point (according to internal documents) because users will not get the same quality Verizon experience while using it (which makes me think it will be a little sketchy at times). Also, it remains to be seen whether the Bionic will have this or not. It has not been rumored yet, but it is certainly possible.
FM radio - while the Bionic is not rumored to have one yet, the X had one so I'm confident the Bionic will too.
External speaker - the TB's will be big and probably louder and sound better, but the Bionic will still have a speaker (just not as visible and big as the TB's)
DLNA - the X had DLNA, so I suspect the Bionic will too. Its probably just becoming a standard feature on Moto phones, so not listed in early spec sheets yet. Thus, it will most likely be able to do both DLNA and HDMI.
Bootloader - both phones will have "locked" bootloaders, but the Bolt will get permanent root from the developer community, while the Bionic will not. This makes the HTC phone much more "hacker-friendly." This only becomes an issue if you want to root and put custom roms on your phone, etc. If you are not into that techy stuff, then this is a non-issue.
Clocking/cores - the Bolt beat each core individually of the Bionic, but putting the two together, the Bionic has a higher total quadrant score. What does this mean? Not much, quadrant scores are easily manipulable. The OS on the Bionic and Android software itself are not optimized for dual core yet, so there will be very little advantage in having dual core for a while (except maybe gaming?). Maybe by the fall or winter they will be able to utilize dual core better, and have apps that can take advantage.
bionic also will have that same tall skinny lcd that the X has, which to me is VERY uncomtorable to type on in portrait model. Yes, its better for watching movies(esp with having more pixels in 16:9) but Im not gonna be watching any movies on a 4.3" screen as the anguish and squinting just aint worth my time. The evo/deseire hd/TB has a much more typing friendly screen, and IMHO makes the device look much more balanced. And the dual core would be nice in the TB, but i suspect we wont see that until feburary of next year(qualcomm loves to delay everything), and its really only useful for gaming anyways...