My bad, got ASROC and SUBROC mixed up, apologies for typing before morning coffee.
Pretty close anyway. ASROC and the more modern vertical launch ASROC were surface ship launched while the Subroc is submarine launched, but all are anti submarine weapons.
Harpoon is an anti surface ship weapon.
And while ASROC had (no longer) a nuclear and conventional torpedo option, the SUBROC had only a nuclear option. The use, I assume, is for long range time urgent ASW, giving the target no warning and no chance of escape. SeaLance was suppose to replace it but the end of the Cold War ended funding, leaving a vacancy in what the SUBROC did. The Mark-48 ADCAP torpedo is the only anti sub weapon on US subs now from what I understand.
The Russians retain the SS-N-15 Starfish which is very similar in function.