publisher vs publishing firm

publisher and publishing firm both are nouns.

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

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

Other synonyms of publisher include publishing company, publishing house.

publisher (noun)	publishing firm (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