publisher vs publishing company

publisher and publishing company both are nouns.

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

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

Other synonyms of publisher include publishing firm, publishing house.

publisher (noun)	publishing company (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