Why are 318's low HP and torque?

Hello everyone,
I wanted to figure out why 318 engines are rated so much lower than 340 and 360 engines? Other than the smaller cubic inches, is it only the compression that is lacking in order to wake up the 318 engines? Or is it completely different engineering that made it so much tamer? Just a random curiosity I have and I know y'all can tell me what's up! Thanks everyone.