heavy torpedo vs heavyweight torpedo

heavy torpedo and heavyweight torpedo both are nouns.

Word	Noun	Adjective	Verb	Adverb
heavy torpedo	Yes	No	No	No
heavyweight torpedo	Yes	No	No	No

As nouns, heavy torpedo and heavyweight torpedo are synonyms defined as:

heavy torpedo and heavyweight torpedo: a torpedo that carries a warhead of at least 450 kg, used primarily as a standoff weapon, particularly by submerged submarines.

heavy torpedo (noun)	heavyweight torpedo (noun)
a torpedo that carries a warhead of at least 450 kg, used primarily as a standoff weapon, particularly by submerged submarines.	a torpedo that carries a warhead of at least 450 kg, used primarily as a standoff weapon, particularly by submerged submarines.