abortion vs stillbirth

abortion and stillbirth both are nouns.

Word	Noun	Adjective	Verb	Adverb
abortion	Yes	No	No	No
stillbirth	Yes	No	No	No

As nouns, stillbirth is a hyponym of abortion; that is, stillbirth is a word with a more specific, narrower meaning than abortion:

Other hyponyms of abortion include miscarriage, spontaneous abortion, induced abortion.

abortion (noun)	stillbirth (noun)
termination of pregnancy	a natural loss of the products of conception
failure of a plan