shell diameter normally affects pitch. depth affects volume. shell material and construction also affects a lot of things.
A 20" acrylic will most likely be louder than a 20" wood (assuming the same depth) but the acrylic will be a bit brighter.
Kung same wood, same depth, same heads (and head tensions), and same shell material, the 22" will most likely have a lower pitch compared to the 20".
Kung different wood, same heads (and tensions) and same depth, depende sa wood and shell material (I believe a 20" saturn or bubinga will have a fundamentally lower pitch than a 22" birch).
Maraming factors. I think the best way to tell the difference is to try them