seacoast vs seaboard

seacoast and seaboard both are nouns.

Word	Noun	Adjective	Verb	Adverb
seacoast	Yes	No	No	No
seaboard	Yes	No	No	No

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

Other hyponyms of seacoast include litoral, littoral, littoral zone, sands, landfall, seaside, tideland.

seacoast (noun)	seaboard (noun)
the shore of a sea or ocean	the shore of a sea or ocean regarded as a resort