rubber stamp vs authorisation

rubber stamp and authorisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
rubber stamp	Yes	No	No	No
authorisation	Yes	No	No	No

As nouns, authorisation is a hypernym of rubber stamp; that is, authorisation is a word with a broader meaning than rubber stamp:

Other hypernyms of rubber stamp include authorization, empowerment.

rubber stamp (noun)	authorisation (noun)
routine authorization of an action without questions	the act of conferring legality or sanction or formal warrant
a stamp (usually made of rubber) for imprinting a mark or design by hand	the power or right to give orders or make decisions
	official permission or approval
	a document giving an official instruction or command