Rename is actually changing the name of an object whereas Alias is giving another name (additional name) to an existing object. Rename is a permanent name given to a table or column whereas Alias is a temporary name given to a table or column which do not exist once the SQL statement is executed.
Interesting discussion on Rename vs Alias! For anyone looking for something fun while coding or testing, I’ve also been exploring funny borg names—great way to lighten up your projects while learning.