For the main part, a super-user is just like any other user, and all the information about regular users applies to super-users too.
The exceptions are that:
There is no default REST endpoint to create super-users. They need to be created from command line or Python API. Note that the Python API may be in turn mounted on a REST endpoint through an REST channel but to prevent remote attacks, there is no default one.
Only super-users can create other users - this is opposed to signing up. The difference is that signup is a process which requires confirmation from the person that is about to become a user whereas the right to create users that super-users have means that users created become activated straight-away - they may still need to change their password, for instance, but there is no explicit confirmation step on their part.
Regular users may manage information only about themselves but super-users can access data and metadata about other users too. Note that super-users cannot learn what any other user's password is, this is always secret.
Certain API operations are available for super-users only, e.g. locking another user's account. Each relevant part of documentation states it whether super-user powers are required to carry out a given action.