veto vs oppose

veto is a noun but oppose is not a noun.

Word	Noun	Adjective	Verb	Adverb
veto	Yes	No	Yes	No
oppose	No	No	Yes	No

As verbs, oppose is a hypernym of veto; that is, oppose is a word with a broader meaning than veto:

Other hypernyms of veto include contradict, controvert.

veto (noun)	oppose (noun)
a vote that blocks a decision
the power or right to prohibit or reject a proposed or intended act (especially the power of a chief executive to reject a bill passed by the legislature)

veto (verb)	oppose (verb)
command against	be resistant to
vote against; refuse to endorse; refuse to assent	be against; express opposition to
	set into opposition or rivalry
	fight against or resist strongly
	act against or in opposition to
	contrast with equal weight or force