The wheel shape affects how much of the wheel touches the ground, the overall width of the wheel, and the edges of the wheel.
A skinny riding surface is going to slide easier than a wider riding surface because there is more wheel in touch with the ground.
A really wide wheel is going to be heavier than a skinny wheel because it requires more material.
Wheels with edges that have a sharper radius will stay locked on grinding tricks whereas a rounded edge wheel will be easier to get in and out of grinds.
Wheels with a completely squared edge aren’t ideal for sliding ledges or powersliding because the edge can chip.