liberal arts vs subject field

liberal arts and subject field both are nouns.

Word	Noun	Adjective	Verb	Adverb
liberal arts	Yes	No	No	No
subject field	Yes	No	No	No

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

liberal arts: studies intended to provide general knowledge and intellectual skills (rather than occupational or professional skills)
subject field: a branch of knowledge

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

liberal arts (noun)	subject field (noun)
studies intended to provide general knowledge and intellectual skills (rather than occupational or professional skills)	a branch of knowledge