tail fin vs ornamentation

tail fin and ornamentation both are nouns.

Word	Noun	Adjective	Verb	Adverb
tail fin	Yes	No	No	No
ornamentation	Yes	No	No	No

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

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

Other hypernyms of tail fin include decoration, ornament.

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