It's subjective, but I'd say that rice cooked under pressure is more chewy and has a stronger flavor of its own. The higher temperature produces a more pronounced Maillard reaction, which not only increases flavor but also turns the rice slightly yellow as if it had been toasted. This is exactly what you want in a strongly flavored Korean dish like stone-bowl bibimbap.

Rice cooked without pressure comes out light and fluffy. This is more appropriate for sushi where you don't want the flavor of rice to overwhelm or collide with the subtle flavor of the other ingredients.