ommatidium vs simple eye

ommatidium and simple eye both are nouns.

Word	Noun	Adjective	Verb	Adverb
ommatidium	Yes	No	No	No
simple eye	Yes	No	No	No

As nouns, simple eye is a hypernym of ommatidium; that is, simple eye is a word with a broader meaning than ommatidium:

ommatidium: any of the numerous small cone-shaped eyes that make up the compound eyes of some arthropods
simple eye: an eye having a single lens

Other hypernyms of ommatidium include ocellus, stemma.

ommatidium (noun)	simple eye (noun)
any of the numerous small cone-shaped eyes that make up the compound eyes of some arthropods	an eye having a single lens