It seems I didn't make myself clear. @Penny asked what are the differences and there are. Ordered lists require...ordination, let's look in the dictionary: The noun ordination comes from the Latin word ordinare, meaning “put in order.”
Primary Meanings of ordination
the act of ordaining; the act of conferring (or receiving) holy orders
logical or comprehensible arrangement of separate elements
an orderly grouping (of things or persons) considered as a unit; the result of arranging
A list look ordered because it follows a logical arrangement, in our brains, but we need a logical indicator of importance in code. <ul> can't receive the type="" attribute, because there are no itens that must become first, <ol> receive type="" attribute. <ol> don't receive list-style-type, because it has to be ordered with A, a, I, i or a number, <ol> must sign wich item has priority. <ul> receive list-style-type because it has no ordered itens, they're just below each other.
Suppose you have to code something that only reads the second itens of lists.
Suppose you have to code something that reads the third itens of a list but only the lists that have the type="A".