approval vs adoption

approval and adoption both are nouns.

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

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

approval (noun)	adoption (noun)
the formal act of approving	the act of accepting with approval; favorable reception
a message expressing a favorable opinion	the appropriation (of ideas or words etc) from another source
a feeling of liking something or someone good	a legal proceeding that creates a parent-child relation between persons not related by blood; the adopted child is entitled to all privileges belonging to a natural child of the adoptive parents (including the right to inherit)
acceptance as satisfactory