I'm just a watcher not a runner, but that make no sense to me, why there a category for no Turbo ? it just easy skip for story and animation, it dosn't effect the game play at all. or am I missing anything?

Turbo category is hard to watch for a lot of people because it goes so fast. It's also more difficult to execute for similar reasons. There's also some slight differences in some strategies between the two, for example wasting turns with Turbo (e.g. Angelica fight) is faster with spamming attacks, on No Turbo it's faster to use the Move command.