Difference between fake and real iPhone 4?

As much as possible, tell the physical difference. We have a friend without pentalobe screws so we thought its fake but we really can't tell that it's fake. 10 points for best answer

Added (1). Thanks for your answers. But I need to know if all iPhones have pentalobe screws or if old iPhone 4 don't have it.

Well the real one has better graphics better quality parts better battery better everything
the only similarity is the looks from a distance
by the way the real one has a heat sensitive screen so you can use your finger
you can't on the fake one
basically the fake one is just fake
it sucks
and on start up you hear this F***ed up chinese sound

A real iPhone will be running iOS. You can't fake that, although there are some Android OSes that can emulate the look of iOS.

Buy from a named store or the apple store and you don't have to worry about it.