ice pack vs ice bag

ice pack and ice bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
ice pack	Yes	No	No	No
ice bag	Yes	No	No	No

As nouns, ice pack and ice bag are synonyms defined as:

ice pack and ice bag: a waterproof bag filled with ice: applied to the body (especially the head) to cool or reduce swelling

ice pack (noun)	ice bag (noun)
a waterproof bag filled with ice: applied to the body (especially the head) to cool or reduce swelling	a waterproof bag filled with ice: applied to the body (especially the head) to cool or reduce swelling
a large expanse of floating ice