An administrative user has no restrictions; these users can do things like re-assign ownership of all database tables, all schemas, and all databases; assign to or remove roles from all usernames; create and destroy usernames, including other administrative users; and create and destroy all tables, all schemas, and all databases.
In short, administrative users are all-powerful.
Needless to say, administrative usernames should be meted out sparingly. They should also be used sparingly.
Every person who has an administrative username should also have an ordinary username. The ordinary username carries much less risk of inadvertent, subtle or not-so-subtle, destruction. Login as an administrative user only when absolutely necessary.