Do iPhones need a different data plan?

I'm getting an iPhone tomorrow, and i want to know if it will mess up my bill? I already have a Smart phone and I pay for a data plan every month. Do the iPhones need a different kind of plan or can I keep the one i have? I'm on a family plan also and the admin of the plan has an Android as do i. Will this change everything> What should I expect? I have AT&T!

I had a Blackberry when I was on ATT with a data plan. I got an iPhone, and they switched me to an iphone data plan and it didn't affect my bill.