abortus vs fetus

abortus and fetus both are nouns.

Word	Noun	Adjective	Verb	Adverb
abortus	Yes	No	No	No
fetus	Yes	No	No	No

As nouns, fetus is a hypernym of abortus; that is, fetus is a word with a broader meaning than abortus:

abortus: a human fetus whose weight is less than 0.5 kilogram when removed or expelled from the mother's body
fetus: an unborn or unhatched vertebrate in the later stages of development showing the main recognizable features of the mature animal

Other hypernyms of abortus include foetus.

abortus (noun)	fetus (noun)
a human fetus whose weight is less than 0.5 kilogram when removed or expelled from the mother's body	an unborn or unhatched vertebrate in the later stages of development showing the main recognizable features of the mature animal