Coup and Resistance, while both games of deception and social engineering, differ in how their deception plays out.
Coup’s deception is confrontational. On every turn you facedown an opponent and challenge them to a guessing game directly. The game relies on you deceiving others to perform actions optimally. If no one lies or no one confronts anyone’s lies, the game ends very quickly.
Resistance’s is less confrontational. Your goal is to evade detection and deceive the group as a whole. In addition, not everyone needs to lie. If you aren’t assigned the role of a spy, you are spared the act of deceiving the group.
I have found that this results in two polar opposites of player groups. A group of players who aren’t confrontational in nature find Coup lackluster because everyone just settles into an optimal or suboptimal strategy and the game ends without much fanfare.
Resistance on the other hand, bores players who want to challenge each other. Be dealt the wrong role and they find themselves just sitting around for 15 minutes. Yes the accusation and voting rounds provide some entertainment, but it just isn’t the same.
This is all anecdata of course. I like both games, and admittedly I might be stuck in some kind of local maxima due to my own personality and personal history defining the kind of people I play games with.
As a final parting thought: Coup with a mix of highly confrontational and pacifist players also never goes well either.