Absolutely no difference. An AC is a heat pump.

If you're an aussie, you know it as a reverse cycle. A shockingly large amount of the rest of the world only know window unit air cons

When cooling they act the same way (and similar to a fridge, it's pretty basic tech, scale is what makes them more efficient) but if your climate makes a heatpump viable you're trading out a heavily polluting heat source instead. Swings and roundabouts

Except it's not, and, as previously mentioned, they are more efficient.