ology vs subject area

ology and subject area both are nouns.

Word	Noun	Adjective	Verb	Adverb
ology	Yes	No	No	No
subject area	Yes	No	No	No

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

ology: an informal word (abstracted from words with this ending) for some unidentified branch of knowledge
subject area: a branch of knowledge

Other hypernyms of ology include bailiwick, discipline, field, field of study, study, subject, subject field.

ology (noun)	subject area (noun)
an informal word (abstracted from words with this ending) for some unidentified branch of knowledge	a branch of knowledge