As nouns the difference between deism and reism
is that deism
is a philosophical belief in the existence of a god (or goddess) knowable through human reason; especially, a belief in a creator god unaccompanied by any belief in supernatural phenomena or specific religious doctrines while reism
is (philosophy) a form of concretism.
The religious philosophy and movement that became prominent in England, France, and the United States in the 17th and 18th centuries that rejects supernatural events (prophecy, miracles) and divine revelation prominent in organized religion, along with holy books and revealed religions that assert the existence of such things.
Reference to the 17th and 18th century movement is more frequently capitalized, while reference to the general philosophy or belief is more frequently not capitalized.