What are the differences between Diamond, Pearl, and Platinum?

Question

The Games not the the precious stones/metal. I want to know the main differances as I have only played platinum

Comments

Well, for starters, you're characters look different, and you can go to the Distortion World in Platinum.

Answer 1

You can catch more pokemon in Platinum that you couldn't catch in Pearl/Diamond before beating the Elite Four.

You can get both dialga and palkia

You can catch giratina before you fight the elite four

Some of the routes and buildings have been redesigned