As I understand, you want to know the main differences between the Slingbox Classic and the Slingbox SOLO.
The Slingbox SOLO allows you to connect a HD TV source, using the Component (RGB) cables. However, you will only get the Standard definition quality.
The following links will provide you with all the information about the Slingbox SOLO and all of its features.
Slingbox SOLO features
You can also take advantage of the Slingbox Upgrade Program.