I will do my camera, a more expensive camera, and a cheaper camera. I will just do a brief review. The prices are for the actual body, no lens.
Canon EOS 60D ($899):
Resolution: 18MP
Sensor: 0.88 x 0.59" (22.3 x 14.9mm) APS-C CMOS
Sensitivity: ISO 100 - 6400 H: 12800
Shutter Speeds: 1/8000 to 30 seconds, bulb - X-sync at 1/250
Viewfinder Coverage: 96%
Weight: 23.8 oz (675g) - Body only
*LCD flips out.
Canon EOS Rebel T2i ($679/$777 BH & Best Buy have different prices):
Resolution: 18MP
Sensor: 22.3mm x 14.9mm (APS-C size)
Sensitivity: ISO 100 - 6400 H: 12800
Shutter Speeds:1/4000 sec. to 30 sec., bulb
Viewfinder Coverage: 95%
Weight: 18.7 oz (530g) - Body only
Canon EOS 5D Mark II ($2,499):
Resolution: 21.1MP
Sensor: 36 x 24mm CMOS
Sensitivity: ISO 100-6400 (expandable to 50, 12800, and 25600)
Shutter Speeds: 1/8000 - 30 sec, bulb
Viewfinder Coverage: 98%
Weight: 28.6oz. (810g) body only
So this is just a few things for each camera. I am sure that there are a lot more things that make them different, but I'm not sure what differences really matter.
I can see instantly that the 5D Mark II has a lot bigger difference in the sensor, which makes it a very good camera. This really reflects in the price too. I almost went with the Rebel T2i, but I really wanted the LCD screen that can flip out and rotate. The other 2 camera don't have this ability. It also helps protect my screen because when I'm not using it, the screen is flipped inside. I'm not sure if that makes sense. The Rebel T2i and 60D are similar, with a little bit in differences.