How to tell the difference between an iphone 2 and 3?

How can you tell the difference between an iphone 2 and 3?

The greatest difference is in their names…

Its depend on the quality & features

Here you go

ik i'm bad describing but in this picture from upper left corner to bottom right it iphone (2), iphone 3G/3GS, and Iphone 4

ALSO AN EASY Way TO TELL ITS THE ORIGINAL IPHONE IS IT HAS NO 2 SCREWS ON THE BOTTOM