Shamisen vs. Biwa: What's the Difference?

Shamisen and Biwa Definitions
Shamisen
A Japanese musical instrument resembling a lute, having a very long neck and three strings played with a plectrum.
Biwa
A plucked lute, originating in the classical and traditional music of Japan, characterized by a pear-shaped body and four or five high frets, giving the instrument a distinctively twangy tone.
Shamisen
(musical instrument) A kind of three-stringed Japanese fretless lute.
Shamisen
A Japanese stringed instrument resembling a banjo with a long neck and three strings and a fretted fingerboard and a rectangular soundbox; played with a plectrum