Diplomatic pouch and Mail pouch

Diplomatic pouch noun - A mail pouch that is sealed shut and that is used to carry communications between a legation and its home office.

Mail pouch and diplomatic pouch are semantically related. In some cases you can use "Mail pouch" instead a noun phrase "Diplomatic pouch".

Mail pouch noun - Pouch used in the shipment of mail.

Diplomatic pouch and mail pouch are semantically related. Sometimes you can replace phrase "Diplomatic pouch" with "Mail pouch", this phrases are similar.