iPhone- first iPhone that came out.
iPhone 3G- has a better touch screen and it's smaller.
iPhone 3GS- is also a little more advanced then the last one.
iPhone 4- is bigger and a little more skinnier than the last one.
iPhone 4s- it's like a update from the 4.
iPhone 5- is longer and has a better camera and available data.
iPhone 5c- is the same a the iPhone 5 but it has a color on the back (with out case).
iPhone 5s- is the same as the other fives but it has a finger print, which means you can open it by putting your finger on the circle.
iPhone 6/6 plus- a lot longer and skinnier. It also has better camera and storage etc.
iPhone 6s/6s plus- this iPhone is only a little more advanced the the last iPhone.
iPhone7/7 plus- better camera and bigger. It's supposed to be water proof and the button is a little different.