threshing machine vs thresher

threshing machine and thresher both are nouns.

Word	Noun	Adjective	Verb	Adverb
threshing machine	Yes	No	No	No
thresher	Yes	No	No	No

As nouns, threshing machine and thresher are synonyms defined as:

threshing machine and thresher: a farm machine for separating seeds or grain from the husks and straw

Other synonyms of threshing machine include thrasher.

threshing machine (noun)	thresher (noun)
a farm machine for separating seeds or grain from the husks and straw	large pelagic shark of warm seas with a whiplike tail used to round up small fish on which to feed
	a farm machine for separating seeds or grain from the husks and straw