freestyling vs improvisation

freestyling and improvisation both are nouns.

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

As nouns, improvisation is a hypernym of freestyling; that is, improvisation is a word with a broader meaning than freestyling:

freestyling: A form of rapping in which the emcee makes up lyrics while rapping.
improvisation: a creation spoken or written or composed extemporaneously (without prior preparation)

freestyling (noun)	improvisation (noun)
A form of rapping in which the emcee makes up lyrics while rapping.	an unplanned expedient
	a performance given extempore without planning or preparation
	a creation spoken or written or composed extemporaneously (without prior preparation)