seawall vs breakwater

seawall and breakwater both are nouns.

Word	Noun	Adjective	Verb	Adverb
seawall	Yes	No	No	No
breakwater	Yes	No	No	No

As nouns, seawall and breakwater are synonyms defined as:

seawall and breakwater: a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away

Other synonyms of seawall include bulwark, groin, groyne, jetty, mole.

seawall (noun)	breakwater (noun)
a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away	a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away