Yes it does mean double ended queue. I'll assume you mean a python list when you say simple array. One drawback of lists is that you cannot add a new element to the start of a list in constant time (with a python list it requires O(n) time), whereas you can with a deque.
I had a script a while back that created really long lists at runtime by continually appending data as it came over the wire. The lists would quickly get so long that I needed to remove items from the beginning to conserve memory though because reasons I could only remove items one at a time. Long story short, converting those lists to collections.deque and making use of popleft() rather than "del l[0]" improved performance considerably.
