Most people write lists when they go shopping, and they may sometimes number the lists and sometimes not add numbers. Even if a list doesn't have numbers, a doodler may add a circle or some other marking beside the lists. For visits to more than one store, the list may be divided into headings of hardware items and grocery items. Any numbering may start over with 1 when the headings change or may be continued without restarting. So everyone knows about lists.
Items identified by numbers are in ordered lists. Instead of 1, 2, 3, etc, one could use alphabetic characters, either lower case or upper case, or could even use Roman numerals instead of our Arabic numbers. If the list is divided in categories under headings, we would probably call each heading and its items a sub-list. Just as on the shopping list, numbers or alphabetic characters could restart or be continuous. This is how an ordered list that uses default styling appears.
Lists that are not numbered or identified by a, b, c, etc. are unordered lists, and the items on the list can have no marking beside them or can be marked by diamonds, circles, squares, or other markers that have no sequence, for example, images. The diamonds, circles, squares, etc. can be open or filled in. Here is an unordered list that uses default settings.