It is not uncommon for the neophyte to mistake apostates and maleficarum as one and the same. Indeed, the Chantry has gone to great lengths over the centuries to establish that this is so. The truth, however, is that while an apostate is often a maleficar, he need not be so. A maleficar is a mage who employs forbidden knowledge such as blood magic and the summoning of demons, whereas an apostate is merely any mage who does not fall under the auspices of the Circle of Magi (and therefore the Chantry). They are hunted by the templars, and quite often they will turn to forbidden knowledge in order to survive, but it would be a lie to say that all apostates begin that way.
Historically, apostates become such in one of two ways: They are either mages who have escaped from the Circle or mages who were never part of it to begin with. This latter category includes what we tend to refer to as "hedge mages"—those with magical ability out in the hinterlands who follow a different magical tradition than our own. Some of these hedge mages are not even aware of their nature. Undeveloped, their abilities can express themselves in a variety of ways, which the hedge mage might attribute to faith, or will, or to another being entirely (depending on his nature). Some of these traditions are passed down from generation to generation, as with the so-called "witches" of the Chasind wilders or the "shamans" of the Avvar barbarians.
No matter how a mage has become apostate, the Chantry treats them alike: Templars begin a systematic hunt to bring the apostate to justice. In almost all cases, "justice" is execution. If there is some overriding reason the mage should live, the Rite of Tranquility is employed instead. Whether we of the Circle of Magi believe this system fair is irrelevant: It is what it is.