song thrush vs throstle

song thrush and throstle both are nouns.

Word	Noun	Adjective	Verb	Adverb
song thrush	Yes	No	No	No
throstle	Yes	No	No	No

As nouns, song thrush and throstle are synonyms defined as:

Other synonyms of song thrush include mavis, Turdus philomelos.

song thrush (noun)	throstle (noun)
common Old World thrush noted for its song	common Old World thrush noted for its song
	a spinning machine formerly used to twist and wind fibers of cotton or wool continuously