I don’t know the breakdown of the statistics, but yeah there are different kinds and levels of blindness. Blindness can be due to physical damage to the lense, retina, optic nerve, or the visual processing area of the brain. It can be due to clouded lenses like cataracts. It can be due to malformations of the retina, non-functioning cones/rods, or shape of the lens or eyeball itself. Some of those lead to total blindness, but lead to varying degrees of vision impairment, up to and including legal blindness. Some of those can be corrected for with glasses, contacts, surgery or even electronic neural interfaces in some cases. Some are just permanent and can’t be improved.

The kind of blindness I find most interesting is when the eyes and optic nerve function normally, but the party of the brain that processes vision just doesn’t function for various reason, but the part of the brain that processes spatial awareness does still function. Those people have no sight at all, but they are still able to perceive objects and space around them and, for example, avoid obstacles when walking, despite but being able to see the obstacles in a visual sense.