viva vs oral exam

viva and oral exam both are nouns.

Word	Noun	Adjective	Verb	Adverb
viva	Yes	No	No	No
oral exam	Yes	No	No	No

As nouns, viva and oral exam are synonyms defined as:

Other synonyms of viva include oral, oral examination, viva voce.

viva (noun)	oral exam (noun)
an examination conducted by spoken communication	an examination conducted by spoken communication