Stack: A stack follows the Last In, First Out (LIFO) principle, meaning the last element added is the first to be removed. Operations are typically performed at one end, called the "top" of the stack.Queue: A queue follows the First In, First Out (FIFO) principle, meaning the first element added is the first to be removed. Operations are performed at both ends: elements are added at the "rear" and removed from the "front."