long-tailed weasel vs longtail weasel

long-tailed weasel and longtail weasel both are nouns.

Word	Noun	Adjective	Verb	Adverb
long-tailed weasel	Yes	No	No	No
longtail weasel	Yes	No	No	No

As nouns, long-tailed weasel and longtail weasel are synonyms defined as:

long-tailed weasel and longtail weasel: the common American weasel distinguished by large size and black-tipped tail

Other synonyms of long-tailed weasel include Mustela frenata.

long-tailed weasel (noun)	longtail weasel (noun)
the common American weasel distinguished by large size and black-tipped tail	the common American weasel distinguished by large size and black-tipped tail