A stack and a queue are two fundamental data structures that follow distinct principles for adding and removing elements. Specifically, a stack adheres to the Last-In-First-Out (LIFO) principle, whereas a queue follows the First-In-First-Out (FIFO) principle.

To elaborate, a stack is a linear data structure where elements are both added and removed from the same end, referred to as the “top”. This characteristic means that the most recently added element will be the first one to be removed, which is the essence of the LIFO principle. An everyday analogy for a stack is a stack of plates: you can only add or take away plates from the top. In computer science, stacks serve various purposes, including memory management, expression evaluation, and syntax parsing.

Conversely, a queue is also a linear data structure, but its operation is quite different. In a queue, elements are added at one end, known as the “rear”, and removed from the opposite end, called the “front”. This arrangement ensures that the first element added to the queue will be the first one removed, embodying the FIFO principle. A practical analogy for a queue is a line of people waiting for service; the person who has been waiting the longest (at the front of the queue) will be the first to be served. In computer science, queues are utilized in various applications, such as scheduling processes in operating systems, managing requests in web servers, and implementing breadth-first search algorithms.

In summary, the primary distinction between a stack and a queue lies in the order in which elements are handled. In a stack, the last element added is the first to be removed (LIFO), while in a queue, the first element added is the first to be removed (FIFO). Grasping these principles is essential in computer science, as they underpin many algorithms and data structures.