True magic and blessing are controversial terms that are not in common parlance.
According to the Church of Ardia, there is only one branch of magic, and as such the term true magic is heretical. In this doctrine, all magic originates from Versa, and the ability to cast magic is a side effect of a curse intended to corrupt and destroy humanity.
According to the Church of New Ardianism, it's possible to achieve magic-like effects via a power known as blessing. They believe that this power originates from Ardia. Although this claim is unproven, a magically talented person can easily tell that blessings are very different from voidtouched magic; someone who's able to detect casting of magic cannot detect casting of a blessing.
According to Void, true magic is the uncorrupted form of voidtouched magic. Voidtouched magic is the result of the cosmic parasite feeding on humanity's divine knowledge.
It's reasonable to assume that the terms true magic and blessings refer to the same power.