What is the difference between PriorityQueue and Deque?

PriorityQueue stores elements in a sorted order based on their priority (determined by natural ordering or a comparator). The methods poll() and peek() always return the element with the highest priority.

Deque (Double Ended Queue) is a double-ended queue. It allows adding and removing elements from both the front (addFirst(), removeFirst()) and the end (addLast(), removeLast()). It does not guarantee any order of elements unless it is an implementation of Deque like ArrayDeque or LinkedList.

The main difference: PriorityQueue focuses on the priority of elements, Deque on access to both ends of the queue.