The quirk us humans have of assigning a certain \"meaning\" to a colour is called \"synaesthesia\". This capacity means that each hue evokes in our psyche a determinate concept.
Which is why a man in a dark suit of armour invariably represents \"evil\" and one in golden plate mail will always strike the average individual as \"good\". Or another example, the division of the chromatic circle in \"cold\" and \"warm\" colours.
I understand Adeli\'s point, though. A society instinctively tries to delimit the different meanings in conventions according to their ease of recognition (Any form of language being the prime example of this), and it can be a bit odd to see two slightly different hues of blues representing two completely different aspects of magic. Not that it bothers me, particularly, but it is something I had never noticed before.
I am assuming that you are writing a story in which the different ways of magic are involved, and you are trying to recreate a separation of each way through the colours.
I would suggest considering Azure as a green-tainted blue for your story, if you are attempting to make a clearer visual distinction for each way of the arcane arts. And remembering that not only this visual distinction is given by colour alone: Other variables such as differences in garments and their styles, jewelry, amulets, and particular symbols and anything you can think of can help to convey an idea of individuality.
- Golbez