approval vs favour

approval and favour both are nouns.

Word	Noun	Adjective	Verb	Adverb
approval	Yes	No	No	No
favour	Yes	No	Yes	No

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

Other hyponyms of approval include favor, approbation.

approval (noun)	favour (noun)
the formal act of approving	an act of gracious kindness
a message expressing a favorable opinion	souvenir consisting of a small gift given to a guest at a party
a feeling of liking something or someone good	an advantage to the benefit of someone or something
acceptance as satisfactory	an inclination to approve
	a feeling of favorable regard