ice mass vs ice floe

ice mass and ice floe both are nouns.

Word	Noun	Adjective	Verb	Adverb
ice mass	Yes	No	No	No
ice floe	Yes	No	No	No

As nouns, ice floe is a hyponym of ice mass; that is, ice floe is a word with a more specific, narrower meaning than ice mass:

Other hyponyms of ice mass include glacier, berg, iceberg, ice cap, icecap, ice field, floe.

ice mass (noun)	ice floe (noun)
a large mass of ice	a flat mass of ice (smaller than an ice field) floating at sea