Blattella germanica vs water bug

Blattella germanica and water bug both are nouns.

Word	Noun	Adjective	Verb	Adverb
Blattella germanica	Yes	No	No	No
water bug	Yes	No	No	No

As nouns, Blattella germanica and water bug are synonyms defined as:

Blattella germanica and water bug: small light-brown cockroach brought to United States from Europe; a common household pest

Other synonyms of Blattella germanica include Croton bug, crotonbug, German cockroach.

Blattella germanica (noun)	water bug (noun)
small light-brown cockroach brought to United States from Europe; a common household pest	a true bug: large aquatic bug adapted to living in or on the surface of water
	small light-brown cockroach brought to United States from Europe; a common household pest