The term is coming straight from Forbidden Arcana, p. 49: "While most “sparks” have so little magic that they’re not worth consideration, one type, the aware, are."
If you're Awakened at all you have a Magic Rating, of 1 or more. Discipline and education (i.e. spending Karma in the right areas) can improve that until you become exceptional at it, the king of your little area, the"training (and karma) become a magic 10+ powerful mage" - but you're not a mage, you're still a 'spark' because you can only do that one little area instead of a significant section of magic.