landfall vs sighting

landfall and sighting both are nouns.

Word	Noun	Adjective	Verb	Adverb
landfall	Yes	No	No	No
sighting	Yes	No	No	No

As nouns, sighting is a hypernym of landfall; that is, sighting is a word with a broader meaning than landfall:

landfall: the first sighting of land from the sea after a voyage (or flight over water)
sighting: the act of observing

landfall (noun)	sighting (noun)
the first sighting of land from the sea after a voyage (or flight over water)	the act of observing
the seacoast first sighted on a voyage (or flight over water)