publishing firm vs publisher

publishing firm and publisher both are nouns.

Word	Noun	Adjective	Verb	Adverb
publishing firm	Yes	No	No	No
publisher	Yes	No	No	No

As nouns, publishing firm and publisher are synonyms defined as:

Other synonyms of publishing firm include publishing company, publishing house.

publishing firm (noun)	publisher (noun)
a firm in the publishing business	a firm in the publishing business
	a person engaged in publishing periodicals or books or music
	the proprietor of a newspaper