short-lived vs ephemeral

short-lived is not a noun while ephemeral is a noun.

Word	Noun	Adjective	Verb	Adverb
short-lived	No	Yes	No	No
ephemeral	Yes	Yes	No	No

As adjectives, short-lived and ephemeral are synonyms defined as:

Other synonyms of short-lived include fugacious, passing, transient, transitory.

short-lived (noun)	ephemeral (noun)
	anything short-lived, as an insect that lives only for a day in its winged form

short-lived (adjective)	ephemeral (adjective)
lasting a very short time	lasting a very short time