John Gill Commentary Genesis 15:21

"and the Amorite, and the Canaanite, and the Girgashite, and the Jebusite." — Genesis 15:21 (ASV)

And the Amorites The same with the Amorite, (Genesis 10:16); they inhabited both on this and the other side Jordan:

and the Canaanites which were a particular tribe or nation that bore the name of their great ancestor Canaan, see (Genesis 13:7):

and the Girgashites the same with the Gergesenes in (Matthew 8:28); of these see (Genesis 10:16):

and the Jebusites who inhabited Jerusalem and about it, which was first called Jebus, from the founder of this nation, (See Gill on Genesis 10:16).