briefcase bomb vs bomb

briefcase bomb and bomb both are nouns.

Word	Noun	Adjective	Verb	Adverb
briefcase bomb	Yes	No	No	No
bomb	Yes	No	Yes	No

As nouns, bomb is a hypernym of briefcase bomb; that is, bomb is a word with a broader meaning than briefcase bomb:

briefcase bomb: a bomb consisting of an explosive and timer hidden inside a briefcase
bomb: an explosive device fused to explode under specific conditions

briefcase bomb (noun)	bomb (noun)
a bomb consisting of an explosive and timer hidden inside a briefcase	an explosive device fused to explode under specific conditions
	strong sealed vessel for measuring heat of combustion
	an event that fails badly or is totally ineffectual

briefcase bomb (verb)	bomb (verb)
	throw bombs at or attack with bombs
	fail to get a passing grade