Yeah I'm definitely a casual AIC fan; and I feel just about the same regarding Nirvana. That said, I've never, ever considered the two alike in any way. In fact, before I was poisoned by the labels of genres, which I now kind of hate the entire concept of, I thought of them as almost opposites. Nirvana had songs that could put me to in a kind of...drone state of just getting lost in the music, and then wake me up with some very angst-ridden choruses. AIC did the same, but almost exactly opposite in that they were mostly angst and hardcore and sludgy and then had moments of bliss and comfort.
I dunno, that's my own take on it; and I haven't heard all of the songs from either band by the bye, so this is a very casual fan's take on both. But from the songs I've heard (assume I've heard all of the popular ones along with some of their beginning material that is perhaps lesser known or less popular), this is my naive little opinion...just a bit of a cautionary before some avid fan of either band rapes my facehole to shut me up because I've labeled them wrongly or have described what they consider to be a poor description of the music... Another disclaimer: I'm drunk and I don't give a fuck about shit. That shit I took. I'm not even going to flush it cause I'm paying homage to Earth. So fuck, man. Just fuck.
I'm still just listening to Hollow. Stone was alright, I didn't much care for it to be honest though, I just really wanted to like it. Haven't heard Phantom Limb but the name sounds awesome especially cause METALGEARSOLIDFIVEOMGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGUUUUUUUUUUUUUUUHHHHHHHHHHHHHHHHH