set theory vs pure mathematics

set theory and pure mathematics both are nouns.

Word	Noun	Adjective	Verb	Adverb
set theory	Yes	No	No	No
pure mathematics	Yes	No	No	No

As nouns, pure mathematics is a hypernym of set theory; that is, pure mathematics is a word with a broader meaning than set theory:

set theory: the branch of pure mathematics that deals with the nature and relations of sets
pure mathematics: the branches of mathematics that study and develop the principles of mathematics for their own sake rather than for their immediate usefulness

set theory (noun)	pure mathematics (noun)
the branch of pure mathematics that deals with the nature and relations of sets	the branches of mathematics that study and develop the principles of mathematics for their own sake rather than for their immediate usefulness