discipline vs subject field

discipline and subject field both are nouns.

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

As nouns, discipline and subject field are synonyms defined as:

Other synonyms of discipline include bailiwick, field, field of study, study, subject, subject area.

discipline (noun)	subject field (noun)
training to improve strength or self-control	a branch of knowledge
the act of disciplining
the trait of being well behaved
a branch of knowledge
a system of rules of conduct or method of practice

discipline (verb)	subject field (verb)
punish in order to gain control or enforce obedience
develop (a child's or animal's) behavior by instruction and practice; especially to teach self-control