One could probably write an entire book on all of the different types of drywall texture that one might encounter. We will try to address the common ones.
The names below may vary from area to area and even between those who install the texture. Hopefully the descriptions will help you identify what type you have.
Stipple Textures - This type of texture is done by rolling or spraying on a layer of drywall compound and then 'stippling' it with a brush. The pattern may be round, oval or monolithic.
Knock Down Texture - This is often accomplished by adding a third step to the stippled texture. When the texture is partially dry a plastic or rubber trowel is dragged over the stipple to achieve the 'knock down' look.
Roll Textures - This type is done by applying drywall compound to the wall or ceiling with a paint roller. This type is typically used in closets and garages. It is the easiest of all of them to match.
Trowel Texture - These textures are a carry over from the plastering era. As the name implies they are done with a trowel. Spanish texture, the fan pattern on other similar patterns are done in this manner. Sometimes sand or other aggregates are added to the mud or plaster to give the texture a grainy look.
Acoustic Texture - This type is done with special equipment and looks like small beads sprayed onto the ceiling.
Orange Peel - Or spattered textures are also done with spray equipment.