Can someone tell me what the major difference is between between a Leupold Vari-X II and a Vari-X III?

As I look around for a scope for my new rifle I'm looking at the following:

Leupold 6 x 18 x 40 Vari X II Target Matte Duplex for $400

and a

Leupold Tactical Vari-X III 4.5-14x40 Matte Duplex for $500

I'm trying to find out which is the best deal and see what the differences between the two model types.

Any information would be appreciated.

[url]http://www.leupold.com/products/Scope_Feature_Matrix.htm[/url]