nailhead vs decoration

nailhead and decoration both are nouns.

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

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

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

Other hypernyms of nailhead include ornament, ornamentation.

nailhead (noun)	decoration (noun)
flattened boss on the end of nail opposite to the point	the act of decorating something (in the hope of making it more attractive)
something resembling the head of a nail that is used as an ornamental device	something used to beautify
	an award for winning a championship or commemorating some other event