communications vs subject

communications and subject both are nouns.

Word	Noun	Adjective	Verb	Adverb
communications	Yes	No	No	No
subject	Yes	Yes	Yes	No

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

communications: the discipline that studies the principles of transmitting information and the methods by which it is delivered (as print or radio or television etc.)
subject: a branch of knowledge

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

communications (noun)	subject (noun)
the discipline that studies the principles of transmitting information and the methods by which it is delivered (as print or radio or television etc.)	something (a person or object or scene) selected by an artist or photographer for graphic representation
	a branch of knowledge
	some situation or event that is thought about
	the subject matter of a conversation or discussion
	(grammar) one of the two main constituents of a sentence; the grammatical constituent about which something is predicated
	(logic) the first term of a proposition
	a person who owes allegiance to that nation
	a person who is subjected to experimental or other observational procedures; someone who is an object of investigation

communications (adjective)	subject (adjective)
	likely to be affected by something
	being under the power or sovereignty of another or others
	possibly accepting or permitting

communications (verb)	subject (verb)
	make accountable for
	cause to experience or suffer or make liable or vulnerable to
	make subservient; force to submit or subdue