equinoctial vs equinoctial line

equinoctial and equinoctial line both are nouns.

Word	Noun	Adjective	Verb	Adverb
equinoctial	Yes	Yes	No	No
equinoctial line	Yes	No	No	No

As nouns, equinoctial and equinoctial line are synonyms defined as:

equinoctial and equinoctial line: the great circle on the celestial sphere midway between the celestial poles

Other synonyms of equinoctial include celestial equator, equinoctial circle.

equinoctial (noun)	equinoctial line (noun)
the great circle on the celestial sphere midway between the celestial poles	the great circle on the celestial sphere midway between the celestial poles

equinoctial (adjective)	equinoctial line (adjective)
relating to an equinox (when the lengths of night and day are equal)
relating to the vicinity of the equator