I started off with the free version but later purchased the other one. Honestly, I don't recall what the difference was between the two.
Mike
I did some checking. The paid version has no ads and allows uploads to Box, Dropbox, Evernote, Expensify, and Google Drive.
Edited again to add:
If you have an iPhone, this weeks free app in the app store is Scanner Pro by Readdle, FYI.