nailhead vs ornamentation

nailhead and ornamentation both are nouns.

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

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

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

Other hypernyms of nailhead include decoration, ornament.

nailhead (noun)	ornamentation (noun)
flattened boss on the end of nail opposite to the point	the act of adding extraneous decorations to something
something resembling the head of a nail that is used as an ornamental device	something used to beautify
	the state of being ornamented