When equalizing during scuba, you're upright and can draw in a full lung of air before blowing your nose. So the air already tries to go "up" to your head, and

When equalizing during scuba, you're upright and can draw in a full lung of air before blowing your nose. So the air already tries to go "up" to your head, and with a fully expanded lung it's easy to "blow" the air out. When freediving, however, this is more complicated. Your body is upside down, so the air floating up goes towards your stomach, not your ears where you want it. And since you only have the same air you started with at the surface, your lungs get compressed. So at 10m your lungs are only "half full". Then it becomes quite hard to actually blow any air out of them to equalize. To avoid the mask squeeze, a freediver also have to let some air out of the nose to fill the mask. However, that air is much more valuable to a freediver. So often one use a mask with much less volume. Or even smaller goggles filled with water to avoid having to waste the air. Latter mostly for competitions, though. I personally freedive to see stuff underwater, heh.