The difference between the soul of an ant and an orca is that the ant is not self-aware, the orcas' soul is.
Both animals should be respected in the same degree. None of these animals should be killed recklessly. But as far as I'm aware ants don't live in parks, do they? No one goes around and catches them, puts them in plastic containers only to transport them around the globe and put them in a tank? Orcas live in the open ocean and swim hundreds of miles every day. In a tank they can't do that any longer. There is much scientific evidence that orcas suffer in captivity. Can ants suffer to the same degree if caught and put into a park? I'm not an ant expert but as far as I'm aware insects aren't horribly intelligent creatures that merely act on instinct. Orcas are much like us, they have an additional part of their brain responsible for emotions, one that we don't have. They are self-conscious creatures like us, so are other dolphin species.
Scientists like Dr. Naomi Rose and Dr. Ingrid Visser both argue that captivity damages these creatures and it's backed up by statistics. 87% of all orcas that have been caught since the 60s have died within 10 years of their confinement. Most orcas die prematurely. In captivity they live reduced life spans by roughly 50%.
Depending on how big Ocean Kingdom's orca pool will be, these 2 orcas will likely die within the first 5-10 years. Some wild caught orcas didn't even survive more than a few days.