waist pack vs belt bag

waist pack and belt bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
waist pack	Yes	No	No	No
belt bag	Yes	No	No	No

As nouns, waist pack and belt bag are synonyms defined as:

waist pack and belt bag: a small pouch (usually with a zipper) that attaches to a belt and is worn around the waist

waist pack (noun)	belt bag (noun)
a small pouch (usually with a zipper) that attaches to a belt and is worn around the waist	a small pouch (usually with a zipper) that attaches to a belt and is worn around the waist