Near the bottom of both pages for these cases there is a link for tech specs. That opens a PDF and shows the case in good detail.curious what the difference is. their website does not really explain the difference.
And the impact case actually covers more of the front of the phone. There is another thread where a guy with the commuter dropped his Evo 3d and it landed on its face, and because there is no protection on the front his screen cracked. I guess the commuter is more expensive due to aesthetics. For protection I recommend the impact series(like I had on my original Evo) or the defender(what I now have on the 3d).
Since the impact uses a thicker type of silicone, the bulk difference between it and the defender isnt too severe. People say the defender isnt pocket friendly, but since I wear mostly cargo pants/shorts and slacks instead of fitted jeans like my wife I find that it fits in my pocket just fine.since you have had both, how's the bulk of the impact relative to the defender (as best as you can guess since they're different phones)?