receptor vs oculus

receptor and oculus both are nouns.

Word	Noun	Adjective	Verb	Adverb
receptor	Yes	No	No	No
oculus	Yes	No	No	No

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

receptor: an organ having nerve endings (in the skin or viscera or eye or ear or nose or mouth) that respond to stimulation
oculus: the organ of sight

receptor (noun)	oculus (noun)
an organ having nerve endings (in the skin or viscera or eye or ear or nose or mouth) that respond to stimulation	the organ of sight
a cellular structure that is postulated to exist in order to mediate between a chemical agent that acts on nervous tissue and the physiological response