biological weapon vs W.M.D.

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

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

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

biological weapon: any weapon usable in biological warfare
W.M.D.: a weapon that kills or injures civilian as well as military personnel (nuclear and chemical and biological weapons)

Other hypernyms of biological weapon include weapon of mass destruction, WMD.

biological weapon (noun)	W.M.D. (noun)
any weapon usable in biological warfare	a weapon that kills or injures civilian as well as military personnel (nuclear and chemical and biological weapons)