periapsis vs perilune

periapsis and perilune both are nouns.

Word	Noun	Adjective	Verb	Adverb
periapsis	Yes	No	No	No
perilune	Yes	No	No	No

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

periapsis: (astronomy) the point in an orbit closest to the body being orbited
perilune: periapsis in orbit around the moon

Other hyponyms of periapsis include perigee, perihelion, perijove, periselene.

periapsis (noun)	perilune (noun)
(astronomy) the point in an orbit closest to the body being orbited	periapsis in orbit around the moon