oral examination vs examination

oral examination and examination both are nouns.

Word	Noun	Adjective	Verb	Adverb
oral examination	Yes	No	No	No
examination	Yes	No	No	No

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

Other hypernyms of oral examination include exam, test.

oral examination (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