Whats the difference between the motorola rokr and the motorola rizr?

I have the rizr, since I love slider phones, and motorola is a good name. (i had the samsung d415, and the samsung t809 before) does anyone know of a difference between the rokr and the rizr?|||i have the rizr and i think the rokr is just a bit smaller and has a different layout....|||MOTO ROKR IS SPELT WITH AN O MY FRIEND THERE IS NO DIFFERENCE BUT THE O|||rokr is better|||I have a rokr and I LOVE it. It plays mp3s, takes pictures, bluetooth, and all that. But the ledge thingy on the bottom makes it weird to tx with.