What's the difference between a Manager and a User?

When you add users to your Team account you the have option to give them a role of “User” or “Manager”. 

Managers can add add users to the team account and share templates. The account owner can remove these permissions from the G Merge Plus application under Users.

Users cannot add other users to the Team account nor Share templates. They can create their own private templates and use templates that have been shared with them