pang vs afterpains

pang and afterpains both are nouns.

Word	Noun	Adjective	Verb	Adverb
pang	Yes	No	No	No
afterpains	Yes	No	No	No

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

pang: a sharp spasm of pain
afterpains: pains felt by a woman after her baby is born; associated with contractions of the uterus

Other hyponyms of pang include birth pangs, labor pains, labour pains.

pang (noun)	afterpains (noun)
a sudden sharp feeling	pains felt by a woman after her baby is born; associated with contractions of the uterus
a sharp spasm of pain
a mental pain or distress