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Oh, how awful, does it really have to involve DRAGGING objects instead of just CLICKING on them? Yes, compared to the scripting mechanism, the dungeon creation, the management using only hotkeys arranged in an incomprehensible way, and other quirks of their editor for HoMM5, this is simply terrible! But why, then, on the second day of getting acquainted with the HoMM4 editor, can you create a scenario with scripts without using any manuals, while in HoMM5, after a week, you still can't master it?
As for whether it's a scenario or a campaign, it's definitely a campaign because of the unique heroes, the interesting plot, and all the other things mentioned.
If a scenario has all of this, then it's just a draft for a campaign.