nailhead vs ornament

nailhead and ornament both are nouns.

Word	Noun	Adjective	Verb	Adverb
nailhead	Yes	No	No	No
ornament	Yes	No	Yes	No

As nouns, ornament is a hypernym of nailhead; that is, ornament is a word with a broader meaning than nailhead:

nailhead: something resembling the head of a nail that is used as an ornamental device
ornament: something used to beautify

Other hypernyms of nailhead include decoration, ornamentation.

nailhead (noun)	ornament (noun)
flattened boss on the end of nail opposite to the point	something used to beautify
something resembling the head of a nail that is used as an ornamental device

nailhead (verb)	ornament (verb)
	make more attractive by adding ornament, colour, etc.
	be an ornament to