green thumb vs specialty

green thumb and specialty both are nouns.

Word	Noun	Adjective	Verb	Adverb
green thumb	Yes	No	No	No
specialty	Yes	No	No	No

As nouns, specialty is a hypernym of green thumb; that is, specialty is a word with a broader meaning than green thumb:

Other hypernyms of green thumb include forte, long suit, metier, speciality, strength, strong point, strong suit.

green thumb (noun)	specialty (noun)
a special ability to make plants grow	the special line of work you have adopted as your career
	a distinguishing trait
	an asset of special worth or utility