A queue is a linear data structure that follows the First In, First Out (FIFO) principle, where elements are added at the rear and removed from the front. It is commonly used in scenarios like task scheduling, managing resources, and breadth-first search in graphs. On the other hand, a stack follows the Last In, First Out (LIFO) principle, where elements are added and removed from the top. Stacks are often used in backtracking problems, function calls, and evaluating expressions. While queues prioritize the first element for removal, stacks prioritize the most recently added element.