Definitely.
No doubt about it, I can tell the difference. On BD/HD-DVD, the picture is far more detailed with more clarity. The textures show up more and are more deep in comparison to what you get on a standard DVD.
In a store, they often use a demo disc instead of a movie. Not only that, I noticed they don't often hook them all up properly either. Plus a lot of people don't know jack about technology to start with, so that's probably why they end up getting horrible picture quality on their television sets.
I play my DVD movies on the TV through a VGA cable from the Mac and it is displayed at the highest quality possible, but when I switch over to the PS3 to play a Blu-Ray movie... the difference can be seen immediately.
