Vergo has more striking strength and durability with tekkai and haki.
But from what I can gather here and there they seem to have comparable speed. When he lost to Orochi Garou was already quite fast.
And Garou is an expert fighting other humans. Vergo is strong but I think Garou can deflect Vergo hits at that point with water smashing rock, being stronger doesn't mean he can't deflect hits, he can redirect the strength of the opponent.
Garou won't take down vergo in one hit, but he can wear him down bit by bit.
Garou takes it after some time, he will be surprised by Vergo first hits and haki.