landmark vs reference point

landmark and reference point both are nouns.

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

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

Other hypernyms of landmark include point of reference, reference.

landmark (noun)	reference point (noun)
an anatomical structure used as a point of origin in locating other anatomical structures (as in surgery) or as point from which measurements can be taken	an indicator that orients you generally
a mark showing the boundary of a piece of land
an event marking a unique or important historical change of course or one on which important developments depend
the position of a prominent or well-known object in a particular landscape