buoy vs reference point

buoy and reference point both are nouns.

Word	Noun	Adjective	Verb	Adverb
buoy	Yes	No	Yes	No
reference point	Yes	No	No	No

As nouns, reference point is a hypernym of buoy; that is, reference point is a word with a broader meaning than buoy:

buoy: a float attached by rope to the seabed to mark channels in a harbor or underwater hazards; typically brightly-coloured
reference point: an indicator that orients you generally

Other hypernyms of buoy include point of reference, reference.

buoy (noun)	reference point (noun)
a float attached by rope to the seabed to mark channels in a harbor or underwater hazards; typically brightly-coloured	an indicator that orients you generally