Acid has more hallucinations typically, and it's fucking mean intense sometimes. On a decent dose (say, half a tab) you can sometimes end up being barraged by information and emotions that you can't control. Not necessarily unenjoyable, just a fucking wear by the end of it all.

Shrooms are introspective and giggly and benevolent. Acid is kind of like running out of a little hut into a great exciting storm.