earring vs ear cuff

earring and ear cuff both are nouns.

Word	Noun	Adjective	Verb	Adverb
earring	Yes	No	No	No
ear cuff	Yes	No	No	No

As nouns, ear cuff is a hyponym of earring; that is, ear cuff is a word with a more specific, narrower meaning than earring:

earring: jewelry to ornament the ear; usually clipped to the earlobe or fastened through a hole in the lobe
ear cuff: a non-pierced earring of varying size (i.e. small wrap or hook big enough to hang over the whole ear and dangle) worn on the rim of the ear.

Other hyponyms of earring include drop earring, eardrop, pendant earring, ear hook earring, ear wrap, earcuff.

earring (noun)	ear cuff (noun)
jewelry to ornament the ear; usually clipped to the earlobe or fastened through a hole in the lobe	a non-pierced earring of varying size (i.e. small wrap or hook big enough to hang over the whole ear and dangle) worn on the rim of the ear.