fogsignal vs foghorn

fogsignal and foghorn both are nouns.

Word	Noun	Adjective	Verb	Adverb
fogsignal	Yes	No	No	No
foghorn	Yes	No	No	No

As nouns, fogsignal and foghorn are synonyms defined as:

fogsignal and foghorn: a loud low warning signal that can be heard by fogbound ships

fogsignal (noun)	foghorn (noun)
a loud low warning signal that can be heard by fogbound ships	a warning device consisting of a horn that generates a loud low tone
	a loud low warning signal that can be heard by fogbound ships