If you're referring to the "current" 40GB, 80GB, and 160GB models, then no, there is no difference in features between these models. The only real difference is the hard drive size. Also keep in mind, these "current" models do not have PS2 backwards compatibility (although rumor has it it's just a firmware update away
). However, all PS3s have PS1 backwards compatibility.
Sony made it ridiculously easy to change/upgrade hard drives. I'm not just saying that either. They made it "Apple" easy, if that's makes sense. You'll be amazed.
If you're referring to the "current" 40GB, 80GB, and 160GB models, then no, there is no difference in features between these models. The only real difference is the hard drive size. Also keep in mind, these "current" models do not have PS2 backwards compatibility (although rumor has it it's just a firmware update away

Sony made it ridiculously easy to change/upgrade hard drives. I'm not just saying that either. They made it "Apple" easy, if that's makes sense. You'll be amazed.