ice shelf vs shelf ice

ice shelf and shelf ice both are nouns.

Word	Noun	Adjective	Verb	Adverb
ice shelf	Yes	No	No	No
shelf ice	Yes	No	No	No

As nouns, ice shelf and shelf ice are synonyms defined as:

ice shelf and shelf ice: ice that is attached to land but projects out to sea

ice shelf (noun)	shelf ice (noun)
ice that is attached to land but projects out to sea	ice that is attached to land but projects out to sea