As I understand it, basically. Granted, I've never used BBM before. If you try to text someone with iMessage, it will send them an iMessage instead of a text (

As I understand it, basically. Granted, I've never used BBM before. If you try to text someone with iMessage, it will send them an iMessage instead of a text (assuming you have iMessaging capabilities). Aside from being free, the only other real difference seems to be typing notifications. There is also upcoming/beta desktop client integration coming with Mountain Lion, fwiw.