impossible action vs impossibility

impossible action and impossibility both are nouns.

Word	Noun	Adjective	Verb	Adverb
impossible action	Yes	No	No	No
impossibility	Yes	No	No	No

As nouns, impossible action and impossibility are synonyms defined as:

impossible action and impossibility: an alternative that is not available

impossible action (noun)	impossibility (noun)
an alternative that is not available	an alternative that is not available
	incapability of existing or occurring