talent vs knack

talent and knack both are nouns.

Word	Noun	Adjective	Verb	Adverb
talent	Yes	No	No	No
knack	Yes	No	No	No

As nouns, knack is a hyponym of talent; that is, knack is a word with a more specific, narrower meaning than talent:

Other hyponyms of talent include bent, hang, flair, genius, raw talent.

talent (noun)	knack (noun)
natural abilities or qualities	a special way of doing something
a person who possesses unusual innate ability in some field or activity