Hi zedzero, welcome to the forum.
Here's the comparison chart, from the Alwil website.
Probably the more useful of the features is the ability to easily schedule scanning, automatic handling of found malware, and the enhanced user interface. There are a few more differences, as you can see. (This is all subjective, of course.)
If you click on the upgrade banner from the providers' interface (left click the tray icon) there is a discount for the pro. (20% off)
Avast is a great program. A very significant part of what has kept me malware free for about two years.