pouch vs mailbag

pouch and mailbag both are nouns.

Word	Noun	Adjective	Verb	Adverb
pouch	Yes	No	Yes	No
mailbag	Yes	No	No	No

As nouns, mailbag is a hyponym of pouch; that is, mailbag is a word with a more specific, narrower meaning than pouch:

Other hyponyms of pouch include mail pouch, pocket, sporran, tobacco pouch, belt bag, waist pack.

pouch (noun)	mailbag (noun)
a small or medium size container for holding or carrying things	letter carrier's shoulder bag
(anatomy) saclike structure in any of various animals (as a marsupial or gopher or pelican)	pouch used in the shipment of mail
an enclosed space

pouch (verb)	mailbag (verb)
swell or protrude outwards
put into a small bag
send by special mail that goes through diplomatic channels