seashore vs seaboard

seashore and seaboard both are nouns.

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

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

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

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