endowment vs natural ability

endowment and natural ability both are nouns.

Word	Noun	Adjective	Verb	Adverb
endowment	Yes	No	No	No
natural ability	Yes	No	No	No

As nouns, natural ability is a hypernym of endowment; that is, natural ability is a word with a broader meaning than endowment:

endowment (noun)	natural ability (noun)
the act of endowing with a permanent source of income	ability that is inherited
natural abilities or qualities
the capital that provides income for an institution