User License Types

Can anyone explain to me what it means for a user to be considered an Occasional User?

We are aware of Business User and Analysis User (If someone has only logged in with the Viewer Profile, they’re an Analysis User. If someone has logged in with a profile that has editing rights, they’re a Business User.)

we are on Alfabet ver. 10.15

we want to understand the various user license types in order to better manage access of our user community.

Thank you