IED vs petrol bomb

IED and petrol bomb both are nouns.

Word	Noun	Adjective	Verb	Adverb
IED	Yes	No	No	No
petrol bomb	Yes	No	No	No

As nouns, petrol bomb is a hyponym of IED; that is, petrol bomb is a word with a more specific, narrower meaning than IED:

IED: an explosive device that is improvised
petrol bomb: a crude incendiary bomb made of a bottle filled with flammable liquid and fitted with a rag wick

Other hyponyms of IED include gasoline bomb, Molotov cocktail.

IED (noun)	petrol bomb (noun)
an explosive device that is improvised	a crude incendiary bomb made of a bottle filled with flammable liquid and fitted with a rag wick