improvisation vs extemporisation

improvisation and extemporisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
improvisation	Yes	No	No	No
extemporisation	Yes	No	No	No

As nouns, improvisation and extemporisation are synonyms defined as:

improvisation and extemporisation: a performance given extempore without planning or preparation

Other synonyms of improvisation include extemporization.

improvisation (noun)	extemporisation (noun)
an unplanned expedient	a performance given extempore without planning or preparation
a performance given extempore without planning or preparation
a creation spoken or written or composed extemporaneously (without prior preparation)