discipline vs knowledge domain

discipline and knowledge domain both are nouns.

Word	Noun	Adjective	Verb	Adverb
discipline	Yes	No	Yes	No
knowledge domain	Yes	No	No	No

As nouns, knowledge domain is a hypernym of discipline; that is, knowledge domain is a word with a broader meaning than discipline:

Other hypernyms of discipline include domain, knowledge base.

discipline (noun)	knowledge domain (noun)
training to improve strength or self-control	the content of a particular field 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)	knowledge domain (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