"Mirrors"

How does the type of scroll depend on its protection? Aren't scrolls divided by levels?

In SoD, scrolls are indeed divided only by the levels of the spells and have values of 500, 2000, 3000, 4000, and 5000 accordingly.
In HotA, however, control scrolls (Dimension Door, Teleport, Fly) have been removed from levels 4 and 5 and are generated separately with a value of 15000. The values of levels 4 and 5 scrolls have been changed to 8000 and 10000, while the values of the others remain unchanged.