WMD vs weapon system

WMD and weapon system both are nouns.

Word	Noun	Adjective	Verb	Adverb
WMD	Yes	No	No	No
weapon system	Yes	No	No	No

As nouns, weapon system is a hypernym of WMD; that is, weapon system is a word with a broader meaning than WMD:

WMD: 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 WMD include arm, weapon.

WMD (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