null space vs topological space

null space and topological space both are nouns.

Word	Noun	Adjective	Verb	Adverb
null space	Yes	No	No	No
topological space	Yes	No	No	No

As nouns, topological space is a hypernym of null space; that is, topological space is a word with a broader meaning than null space:

null space: a space that contains no points; and empty space
topological space: (mathematics) any set of points that satisfy a set of postulates of some kind

Other hypernyms of null space include mathematical space.

null space (noun)	topological space (noun)
a space that contains no points; and empty space	(mathematics) any set of points that satisfy a set of postulates of some kind