What is the difference between Authentication vs Authorization?

• Authentication is the process of ascertaining that somebody really is who he claims to be.
• Authorization refers to rules that determine who is allowed to do what. E.g. Adam may be authorized to create and delete databases, while Usama is only authorised to read.

Or in short:

• Authentication = login + password (who you are)
• Authorization = permissions (what you are allowed to do)

Also:

• Authentication = Verification
• Authorization = Permissions