As adjectives the difference between presbyterian and unitarian
is that
presbyterian is of or pertaining to a presbyter, or to ecclesiastical government by presbyters; relating to those who uphold church government by presbyters; also, to the doctrine, discipline, and worship of a communion so governed while
Unitarian is pertaining to Unitarianism.
As nouns the difference between presbyterian and unitarian
is that
presbyterian is a person belonging to a church in the tradition of Presbyterianism while
Unitarian is a Christian who does not believe in the traditional doctrine of the Trinity.