What is the difference between "Yehdafem" and "v'Horish"?
Metzudas Tziyon: Yehdafem is to push off and strike. V'Horish is to dispossess.
Malbim: Yehdafem refers to the Kena'ani who already conquered; some of them fled, e.g. Girgashi. Hashem will repel them, that they not return. V'Horish refers to those not yet conquered.