signboard vs scoreboard

signboard and scoreboard both are nouns.

Word	Noun	Adjective	Verb	Adverb
signboard	Yes	No	No	No
scoreboard	Yes	No	No	No

As nouns, scoreboard is a hyponym of signboard; that is, scoreboard is a word with a more specific, narrower meaning than signboard:

signboard: structure displaying a board on which advertisements can be posted
scoreboard: a large board for displaying the score of a contest (and some other information)

Other hyponyms of signboard include billboard, hoarding, sandwich board, shingle.

signboard (noun)	scoreboard (noun)
structure displaying a board on which advertisements can be posted	a large board for displaying the score of a contest (and some other information)