Full magicians gain access to the full range of magical abilities, spellcasting, summoning, and enchanting, as well as offering full access to the astral plane with both astral perception (p. 159) and astral projection (p. 160).
Aspected magicians are only able to utilize one of the three aspects of magic: spellcasting (Sorcery), summoning (Conjuring), or enchanting (Enchanting). They can access the astral plane with astral perception and projection.
Adepts focus all of their magic inward, fueling their talents with their innate ability to pull mana in rather than channel it outward. Due to this physical connection to their magic, they cannot astrally project and only gain the ability to astrally perceive through training. Adepts have a pool of points equal to their Magic that they use to purchase adept powers.
Mystic adepts are a blend of inward and outward magic. They are capable of casting spells, summoning spirits, and enchanting items, but they also channel a portion of their magic inward to fuel adept talents. They are not able to astrally project due to the anchoring effect of their adept powers, but they can astrally perceive.