3S/3NT/4C/4D are all raises of 1H showing:
1 H - 3 S : A void
3 NT: A singleton
4 C : 2 or 3 aces, no singleton/void
4 D : less than 2 aces, no singleton/void.
After 1S opening, all the bids are the same, except that 4H replaces 3S to show a heart void.