That’s what the HA clustering is, yes.
Difference between domain and standalone mode ist just the management of the resources like DB connection and so on via a centralized domain “controller” server (management instance), which isn’t available in standalone mode (you’ll have to configure every instance individualy). But, as I already said, if everything is automated, you won’t need domain mode.
For further info, I suggest to read the wildfly docs on these topics.