Differences between GRANT and REVOKE command

By using the GRANT command you can grant an system level previledge or role to another user. The WITH ADMIN OPTION clause permits permits the guarantee to bestow the privilege or role on other users.

The grantor can revoke the role from the user as well.

Privileges granted can be taken away. An individual with DBA role can revoke CONNECT, RESOURCE and DBA or any other privilege from anyone including DBA