They overlap
Kind of.
Punk and New Wave were the same thing in 1977/8.
Later a distinction was made when the mainstream consumers became interested.
There’s no such thing as post-punk, really, but it would apply mainly to British bands that were punk but began experimenting more.
Like say after 1978.
I’d say post punk means after the Sex Pistols when things opened up in music and bands could do anything.
It means after breaking the msn monopoly on Rock Band crap like Journey, Led Zeppelin, Eagles, etc…ad nauseum.
Here’s the difference between punk and new wave back in the day.
Punk was tea party/Maga. New Wave was Rino/GOPe.
Early everyone was in the same boat. Differences became more apparent over time.