W.M.D. vs weapon system

W.M.D. and weapon system both are nouns.

Word	Noun	Adjective	Verb	Adverb
W.M.D.	Yes	No	No	No
weapon system	Yes	No	No	No

As nouns, weapon system is a hypernym of W.M.D.; that is, weapon system is a word with a broader meaning than W.M.D.:

W.M.D.: a weapon that kills or injures civilian as well as military personnel (nuclear and chemical and biological weapons)
weapon system: any instrument or instrumentality used in fighting or hunting

Other hypernyms of W.M.D. include arm, weapon.

W.M.D. (noun)	weapon system (noun)
a weapon that kills or injures civilian as well as military personnel (nuclear and chemical and biological weapons)	any instrument or instrumentality used in fighting or hunting