Ordered: Remembers what order you put things into it (list, vector, deque, etc.)
Sorted: Keeps contents in an order determined by a comparison predicate (most kinds of trees)
Hash: No guarantees about what order things come out of the collection (typical hash table implementation)
An excellent distinction; unfortunately there are only so many initial letters of relevant words, and I'm already used to S for Set. You could interpret O as sOrted, I suppose, and then use R for oRdered and Q as the data type seQuence, meaning that it has ordering but no other properties.