marking vs ocellus

marking and ocellus both are nouns.

Word	Noun	Adjective	Verb	Adverb
marking	Yes	No	No	No
ocellus	Yes	No	No	No

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

marking: a pattern of marks
ocellus: an eyelike marking (as on the wings of some butterflies); usually a spot of color inside a ring of another color

Other hyponyms of marking include blaze, crisscross, cross, mark, eyespot, shading, dapple, fleck, maculation, patch, speckle, spot, bar, streak, stripe.

marking (noun)	ocellus (noun)
evaluation of performance by assigning a grade or score	an eyelike marking (as on the wings of some butterflies); usually a spot of color inside a ring of another color
the act of making a visible mark on a surface	an eye having a single lens
a pattern of marks
a distinguishing symbol