now that the lifedrive 2.0 software update from palm is out, the TX and the lifedrive are on par software wise, so for most comparisons, we can treat them as equivalent.

The LD/TX start up quicker and have a lot of available software. For instance, as things stand right now, there are email clients available for the palm that are much better than those available for the 770. Also, the palm has many niche applications, e.g. the astronomy tools I use, which at the moment the 770 lacks.
Even though the palm and the 770 have similar amounts of application memory, the 770 processes seem to be much more heavy-weight than palm apps, which is why some have complained about the 770 having too small an amount of memory.
The LD, but not the TX, also has a 4GB HD which is pretty sweet. The palm LD has a 400MHz strong arm processor - the TX a 320 MHz [or something like that], so the life drive in particular benefits from the faster clock speed. [no, I haven't run any benchmarks comparing the nokia's omap processor and the intel xscale processor, but the palm seems a lot faster to me.] The palm also has wake-up timers that allow it to function as a calendar/alarm which are missing on the 770.

The 770 on the other hand, has a much nicer form factor than the LD [but not the tx]. The screen is so much better on the 770. Battery life is exceptional for a device the size of the 770 considering the screen size and use of wifi. The sensitivity of the palm wifi is not very good - the 770 is by contrast very good. Using wifi, the 770 has much better battery life. The opera browser on the 770 is much better than any palm web browser. The 770 supports multitasking, within the limits of it's limited memory, while the palm can only multitask to a very limited degree using background processes. [can't switch back and forth between running procs on a palm, plus only a few programs support it, e.g. pocket tunes]

To recap, the palm is an mature device desparately in need of revolutionary change. The 770 is a new device just getting started with lots of untapped possibilities.