theory of relativity vs relativity theory

theory of relativity and relativity theory both are nouns.

Word	Noun	Adjective	Verb	Adverb
theory of relativity	Yes	No	No	No
relativity theory	Yes	No	No	No

As nouns, theory of relativity and relativity theory are synonyms defined as:

theory of relativity and relativity theory: (physics) the theory that space and time are relative concepts rather than absolute concepts

Other synonyms of theory of relativity include Einstein's theory of relativity, relativity.

theory of relativity (noun)	relativity theory (noun)
(physics) the theory that space and time are relative concepts rather than absolute concepts	(physics) the theory that space and time are relative concepts rather than absolute concepts