pin-tailed duck vs pintail

pin-tailed duck and pintail both are nouns.

Word	Noun	Adjective	Verb	Adverb
pin-tailed duck	Yes	No	No	No
pintail	Yes	No	No	No

As nouns, pin-tailed duck and pintail are synonyms defined as:

pin-tailed duck and pintail: long-necked river duck of the Old and New Worlds having elongated central tail feathers

Other synonyms of pin-tailed duck include Anas acuta.

pin-tailed duck (noun)	pintail (noun)
long-necked river duck of the Old and New Worlds having elongated central tail feathers	long-necked river duck of the Old and New Worlds having elongated central tail feathers