Ah hah! I'm glad there's already a thread about this (although I had to run a search to find it)!
Although I don't know for certain-sure, I think there's two versions available of a Comic Party manga. One through ADV and one through Tokyopop. Tokyopop's version is the one that's more in line with the anime - which brings me to the purpose of my post.
I very much enjoyed the Comic Party anime. It was clean for the most part (could have done without some fanservice and some junk in the mini-episodes) and the characters were interesting. If you watched the anime and expect the manga to be similar, you may want to think again.
The first big difference I noticed was Kazuki's personality. While he was gentle, quiet, and thoughtful in the anime, he's brash, mean, and a bit crazy in the manga. Yuu (my fav character from the anime) seems about the same except she's a little more vulnerable in the manga instead of her untouchable confidence and optimism in the anime. Mizuki is a little more violent (instead of just threatening like in the anime) and even carries around a bat with nails sticking out of the end! And she doesn't hesitate to use it, nor draw blood.
I know the blood is meant to be funny, but it was a little ... disturbing to me.
The next thing I noticed is the amount of language. There's some song lyrics in the background that are actually very nasty (I can't tell if they were in the original manga, or if they're part of the translation) but the F-word is at least twice that I saw. In my opinion, that's a bit much for a 13+.
Then what Kireihana mentioned - the pointless fanservice in the back. In my opinion, this manga should be considered 15+.