I can calf raise as much as I can squat, yet I have pretty small calves relative to my thighs/glutes. What's the deal?

Think of a see-saw at the playground. Put a 50lb kid on one end and a fully grown adult on the other. The adult obviously lifts the kid, right? Put the adult one inch from the center pivot point and guess what, the kid's weight now lifts the adult.

Think of how long your quads are in relation to the length of your tibia. More or less equal. Now think of your calf's length in relation to the length of your foot. Its almost twice as long. That's almost twice the amount of leverage compared to your quads.

This is the difference between the two and why your calves seem so much more capable for their size than your quads.

Leverage.

I would guess you're doing a much larger range of motion relative to each joint, squatting "ass to grass" but doing calf raises just from standing. Your ankles don't move as far generally as your knees, but if you want to maximize calf gains, do them off a ledge so you raise from the bottom of the range of motion to flat-footed.

Calves are insanely strong, in general. They are constantly balancing your entire body's weight with every step and movement you make. Also as others have stated, squat and calf raise are different ranges of motion