firing line vs class

firing line and class both are nouns.

Word	Noun	Adjective	Verb	Adverb
firing line	Yes	No	No	No
class	Yes	No	Yes	No

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

Other hypernyms of firing line include social class, socio-economic class, stratum.

firing line (noun)	class (noun)
the most advanced and responsible group in an activity	education imparted in a series of lessons or meetings
the line from which soldiers deliver fire	elegance in dress or behavior
	a collection of things sharing a common attribute
	people having the same social, economic, or educational status
	(biology) a taxonomic group containing one or more orders
	a body of students who are taught together
	a body of students who graduate together
	a league ranked by quality

firing line (verb)	class (verb)
	arrange or order by classes or categories