line of fire vs route

line of fire and route both are nouns.

Word	Noun	Adjective	Verb	Adverb
line of fire	Yes	No	No	No
route	Yes	No	Yes	No

As nouns, route is a hypernym of line of fire; that is, route is a word with a broader meaning than line of fire:

Other hypernyms of line of fire include itinerary, path.

line of fire (noun)	route (noun)
the path of a missile discharged from a firearm	an open way (generally public) for travel or transportation
	an established line of travel or access

line of fire (verb)	route (verb)
	send via a specific route
	divert in a specified direction
	send documents or materials to appropriate destinations