What is the difference between Roughness and Friction ?

Roughness is a description of a noun and friction is a force. In other words, a surface can be rough to touch but roughness is simply the feeling of friction.
Roughness causes friction, but it doesnt make sense to say friction causes roughness (especially since that if you "friction" something with sandpaper, it becomes smooth, the opposite of rough.-thats a fun way to remember it ;) )