tailfin vs ornamentation

tailfin and ornamentation both are nouns.

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

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

tailfin: one of a pair of decorations projecting above the rear fenders of an automobile
ornamentation: something used to beautify

Other hypernyms of tailfin include decoration, ornament.

tailfin (noun)	ornamentation (noun)
a stabilizer that is part of the vertical tail structure of an airplane	the act of adding extraneous decorations to something
one of a pair of decorations projecting above the rear fenders of an automobile	something used to beautify
	the state of being ornamented