caudal fin vs tail fin

caudal fin and tail fin both are nouns.

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

As nouns, caudal fin and tail fin are synonyms defined as:

caudal fin and tail fin: the tail of fishes and some other aquatic vertebrates

caudal fin (noun)	tail fin (noun)
the tail of fishes and some other aquatic vertebrates	the tail of fishes and some other aquatic vertebrates
	a stabilizer that is part of the vertical tail structure of an airplane
	one of a pair of decorations projecting above the rear fenders of an automobile