Frollo at least genuinely believed he was a righteous man and genuinely thought he was doing God's word, to the point he was horrified and confused at seeing that he was the one who was the sinner right before his death.
The Coachman makes no excuses for any of his actions, has no evil is cool vibe in any way, and his goals and actions are much more barbaric, ruthless, and unnecessary than Frollo's, as he's simply a greedy and sadistic man who wants to amuse himself.