I've never done either but Here's what I've heard/know from common sense -Intensity is all in how much you take -Shrooms have more of a potential for bad trips for most people -Acid lasts longer (about twice as long) -Some report more visuals with acid, some with shrooms, that depends I guess. -Perception: I once read someone on here say that with acid everything makes sense in your mind, while with shrooms it's like everything you once knew is ripped apart. I suppose that's a personal thing though, also, so depending on your personality your perception could vary. With either however your perception is going to change very dramatically.
For me acid has a lot of geometric patterns. While as for with shrooms things seem to look more fluffy and breathing then geometric. Although once while on shrooms i did have the strongest closed eye visuals ever from any drug. I guess it just depends on the users state of mind. I think it varies the same in all of the senses.
Acid is more powerful and lasts longer. It's the ultimate psychedelic - the ultimate drug. If you buy the ticket, be fully prepared to take the ride