There's techniques -- using herbs, using incantations, using sigils -- or, alternatively, using contagion vs using similarity.
There's schools, fire magic, green magic, water magic, etc.
And there's spells that are useful skill sets for a (non-magical) profession, hobby, or task.
I've got a character in a position of authority. Some spells come naturally to his usual sphere, stone magic -- defensive ones, or ones to restrain people. Others -- well, he has a spell to aid in listening in on things, and a spell to help sleep in odd times without throwing his spell cycles off. I think I'm going to have to put in something to indicate he had to learn them by rote. Or one. Perhaps there can be some way that a spell is related to his sphere.