It's been discussed a lot, but the basic bullet points:
1. There are a lot of casual fans at US Jovi shows, who go for a "night out" experience than for a concert. Though that's not a Jovi-specific thing. Most "classic" acts draw those kind of crowds in the US, even Bruce to an extent.
2. Age. I don't know if crowds are skewed younger in Europe or the social norms of concerts are different, but the older a crowd is, the more sedate they tend to be in the States.
3. Seats. Most American arena shows have seats on the floor (in fact in a lot of places they legally have to)*
4. Musical culture clash. Jumping up and down, signing along, standing, being generally energetic are stereotypically associated with (for lack of a better term) young punk kids. In fact, that type of behavior can draw shouts of "sit down and enjoy the show" in my experience. And I don't mean over the top annoying stuff either, just normal concert behavior. Bamboozle last year was a perfect example of said culture clash last year.


Basically, you have a lot of people (not all obviously) who go for the experience of a night out with drinks, dinner, and Livin' On A Prayer as opposed to more die hard music fans.

*I don't think the seats issue is as big as some people make it out to be. I've seen other bands play seated arenas and the crowds have been absolutely apeshit.