under fire vs under attack

under fire and under attack both are adjectives.

Word	Noun	Adjective	Verb	Adverb
under fire	No	Yes	No	No
under attack	No	Yes	No	No

As adjectives, under fire and under attack are synonyms defined as:

under fire (adjective)	under attack (adjective)
subjected to enemy attack or censure	subjected to enemy attack or censure