I have not noticed religious people and non religious people behaving very differently. Atheists just use different reasons for their misbehavior than theists do.
I'm going to mostly agree with you here in that there are certainly the same percentage of nice atheists & religious people, and ******** atheists and religious people. Being religious doesn't make you good, or bad, nor does being atheist.
However there are some very specific maladies that affect relgious people that don't affect atheists. An example is this war on homosexuality that is admittedly getting better, but is still raging in the more religious parts of America. When 200,000 people ran to Chik-Fil-A to support their anti-gay stance, it was all religious people. Atheists and other non-religous people aren't out there protesting gay people, or saying things like some of the popular pastors and religious politicians are saying about gay people (the government should kill gay people, we should put gay people behind fences, etc) Ask people why they feel this way, they will always answer "it's against my religion." So this is one example of a problem very specific to religion.
Another example is parents being upset that their child is dating or marrying someone outside the faith. This is getting less common as generations get less religious, but it's still far too common. I told the story about my Catholic grandmother refusing to come to my wedding because I happend to fall in love with a woman raised in a Jewish family. I know many stories like this and I'll wager most of you do too. Again, this sad problem only affects the religious.
Being atheist or religous doesn't make you good or bad, but there are some very specific bad behaviors that affect only the religious. And I blame the religion not the people themselves. I was raised very religiously and my father passed on terrible attitudes to me about gay people, explaining that it was against God. When I got out into the wider world I became ashamed when I realized I was bigotted against gay people and I realized it was based on my religious upbringing. I don't really thing there are any specific things like this associated with atheism. If someone thinks there are, please explain.