Platonic year vs great year

Platonic year and great year both are nouns.

Word	Noun	Adjective	Verb	Adverb
Platonic year	Yes	No	No	No
great year	Yes	No	No	No

As nouns, Platonic year and great year are synonyms defined as:

Platonic year and great year: time required for one complete cycle of the precession of the equinoxes, about 25,800 years

Platonic year (noun)	great year (noun)
time required for one complete cycle of the precession of the equinoxes, about 25,800 years	time required for one complete cycle of the precession of the equinoxes, about 25,800 years