The main distinction of porn with a story genre from regular porn is the presence of a coherent narrative. Regular porn often jumps straight to the sexual action, while the story genre tries to add some kind of story framework around it. But in the end, both are adult-oriented and feature explicit sexual content.
The main differences could be in the storylines, character designs, and the level of explicitness. Some might focus more on certain themes or fetishes.
There could be no real basis for this claim. It might just be a perception or a stereotype. Or, it could be related to differences in internet usage patterns or local entertainment industries in the south.
Manga porn is basically adult-oriented manga that contains explicit sexual content. It's very different from regular manga, which can cover a wide range of genres and themes without that kind of explicit stuff.
A night with a Kawakami porn comic could involve various sexual scenarios and explicit imagery. It's not suitable for general audiences and is focused on adult entertainment.