hominy grits versus masa harina
Masa harina is quite simply dried and ground hominy.

As to why masa tastes more corny than hominy? I don't know, perhaps grinding it allows more of that internal flavor to be available to your taste buds. As well, masa is either baked or fried to make tortillas, and that cooking process likely enhances the corn flavor the same way that bread toast has an enhanced malt flavor than untoasted bread.