bottlenose dolphin vs bottle-nosed dolphin

bottlenose dolphin and bottle-nosed dolphin both are nouns.

Word	Noun	Adjective	Verb	Adverb
bottlenose dolphin	Yes	No	No	No
bottle-nosed dolphin	Yes	No	No	No

As nouns, bottlenose dolphin and bottle-nosed dolphin are synonyms defined as:

bottlenose dolphin and bottle-nosed dolphin: any of several dolphins with rounded forehead and well-developed beak; chiefly of northern Atlantic and Mediterranean

Other synonyms of bottlenose dolphin include bottlenose.

bottlenose dolphin (noun)	bottle-nosed dolphin (noun)
any of several dolphins with rounded forehead and well-developed beak; chiefly of northern Atlantic and Mediterranean	any of several dolphins with rounded forehead and well-developed beak; chiefly of northern Atlantic and Mediterranean