berg vs ice mass

berg and ice mass both are nouns.

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

As nouns, ice mass is a hypernym of berg; that is, ice mass is a word with a broader meaning than berg:

berg: a large mass of ice floating at sea; usually broken off of a polar glacier
ice mass: a large mass of ice

Other hypernyms of berg include floater.

berg (noun)	ice mass (noun)
a large mass of ice floating at sea; usually broken off of a polar glacier	a large mass of ice