bulletin board system vs bulletin board

bulletin board system and bulletin board both are nouns.

Word	Noun	Adjective	Verb	Adverb
bulletin board system	Yes	No	No	No
bulletin board	Yes	No	No	No

As nouns, bulletin board system and bulletin board are synonyms defined as:

bulletin board system and bulletin board: a computer that is running software that allows users to leave messages and access information of general interest

Other synonyms of bulletin board system include bbs, electronic bulletin board.

bulletin board system (noun)	bulletin board (noun)
a computer that is running software that allows users to leave messages and access information of general interest	a board that hangs on a wall; displays announcements
	a computer that is running software that allows users to leave messages and access information of general interest