futurology vs field of study

futurology and field of study both are nouns.

Word	Noun	Adjective	Verb	Adverb
futurology	Yes	No	No	No
field of study	Yes	No	No	No

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

futurology: the study or prediction of future developments on the basis of existing conditions
field of study: a branch of knowledge

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

futurology (noun)	field of study (noun)
the study or prediction of future developments on the basis of existing conditions	a branch of knowledge