halo vs parhelic circle

halo and parhelic circle both are nouns.

Word	Noun	Adjective	Verb	Adverb
halo	Yes	No	No	No
parhelic circle	Yes	No	No	No

As nouns, parhelic circle is a hyponym of halo; that is, parhelic circle is a word with a more specific, narrower meaning than halo:

halo: a circle of light around the sun or moon
parhelic circle: a luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere

Other hyponyms of halo include parhelic ring, solar halo.

halo (noun)	parhelic circle (noun)
an indication of radiant light drawn around the head of a saint	a luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere
a circle of light around the sun or moon
a toroidal shape