[@SunsetRoses]
I was definitely thinking that there was some sort of inner source, and the two are definitely different, but I was thinking that there's this big gulf of difference. The conceit I was working under was that people that had enough magic within them to cast spells with it were basically the royalty of the magic world. Like the reasons most powerful wizards were old dudes with long white beards or haggard old woman was because they'd spent most of their life cultivating that inner store of magic and then went hog wild in their old age. They can do anything they want so long as they spend enough time developing a spell to do it and have sufficient magic to cast that spell and live. 

People that didn't want to go through this steady build up tapped other sources of energy to make up the difference, with only a tiny investment of their own power to get the ball rolling resulting in the different classes and sub-classes of magic user. But they're not as free in their casting as someone using their own power because, as they're tapping another source, that source gets some input in what happens. So you can't draw power from fire and then use that power to freeze things. They're bound to theme.
 
So Allison would have an almost pathetically tiny store of actual raw power compared to Dianna.