science vs subject field

science and subject field both are nouns.

Word	Noun	Adjective	Verb	Adverb
science	Yes	No	No	No
subject field	Yes	No	No	No

As nouns, subject field is a hypernym of science; that is, subject field is a word with a broader meaning than science:

Other hypernyms of science include bailiwick, discipline, field, field of study, study, subject, subject area.

science (noun)	subject field (noun)
a particular branch of scientific knowledge	a branch of knowledge
ability to produce solutions in some problem domain