What are the differences between the data structures queue and deque from the collections module in Python?

In Python, from the collections module:

• deque (double-ended queue) is a bidirectional queue that allows efficient addition and removal of elements from both ends (left and right). It is implemented as a linked list and is suitable for tasks that require insertions and deletions from both sides.

• queue.Queue is a thread-safe queue for multithreaded programming, implementing the FIFO (first-in, first-out) principle. It is designed for data exchange between threads and provides blocking operations put() and get().

In summary:

• deque is a versatile, fast structure for a bidirectional queue, not thread-safe by default.
• queue.Queue is a specialized thread-safe queue with blocking operations.

Example of using deque:

from collections import deque

q = deque()
q.append('right')  # add to the right
q.appendleft('left')  # add to the left
print(q)  # deque(['left', 'right'])

q.pop()  # remove from the right
q.popleft()  # remove from the left

Example of using queue.Queue:

import queue

q = queue.Queue()
q.put(1)
item = q.get()  # blocks if the queue is empty