viva voce vs examination

viva voce and examination both are nouns.

Word	Noun	Adjective	Verb	Adverb
viva voce	Yes	No	No	Yes
examination	Yes	No	No	No

As nouns, examination is a hypernym of viva voce; that is, examination is a word with a broader meaning than viva voce:

Other hypernyms of viva voce include exam, test.

viva voce (noun)	examination (noun)
an examination conducted by spoken communication	the act of examining something closely (as for mistakes)
	the act of giving students or candidates a test (as by questions) to determine what they know or have learned
	a detailed inspection of your conscience (as done daily by Jesuits)
	a set of questions or exercises evaluating skill or knowledge
	formal systematic questioning

viva voce (adverb)	examination (adverb)
orally