What have been changed since the light of iPad 1

For not so long ago, the fifth generation of Apples iPad was released, but what have been changed since the first generation, iPad 1

The first iPad generation was released in April 3, year 2010 and after that we got 3 more released, called generation, 2, 3 and 4.

And now finely, the new Apple iPad Air on September 18, 2013.

So what are the different in speed, because when it come to designed, they are very similar.

This video show the different speed between the 5 models in a cool way.