troth vs promise

troth and promise both are nouns.

Word	Noun	Adjective	Verb	Adverb
troth	Yes	No	No	No
promise	Yes	No	Yes	No

As nouns, promise is a hypernym of troth; that is, promise is a word with a broader meaning than troth:

troth: a mutual promise to marry
promise: a verbal commitment by one person to another agreeing to do (or not to do) something in the future

troth (noun)	promise (noun)
a solemn pledge of fidelity	grounds for feeling hopeful about the future
a mutual promise to marry	a verbal commitment by one person to another agreeing to do (or not to do) something in the future

troth (verb)	promise (verb)
	make a promise or commitment
	promise to undertake or give
	make a prediction about; tell in advance
	give grounds for expectations