perigee vs point of periapsis

perigee and point of periapsis both are nouns.

Word	Noun	Adjective	Verb	Adverb
perigee	Yes	No	No	No
point of periapsis	Yes	No	No	No

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

perigee: periapsis in Earth orbit; the point in its orbit where a satellite is nearest to the Earth
point of periapsis: (astronomy) the point in an orbit closest to the body being orbited

Other hypernyms of perigee include periapsis.

perigee (noun)	point of periapsis (noun)
periapsis in Earth orbit; the point in its orbit where a satellite is nearest to the Earth	(astronomy) the point in an orbit closest to the body being orbited