There are many curl types out, Type 3 Curls and Type 4 Curls. They are broken down into sub-categories from a-c, for example, 3a, 3b, 3c, 4a, 4b, 4c. The sub-categories categorize the size of the curl.
Hair texture is also another factor in hair, for example: Fine, Medium, & Coarse. It is possible to have multiple curl sizes and multiple hair textures in one head.