Even with the substantial difference of the Sanshin between the shamisen, what are the similarities? Positions, music etc…:3
yea it kind of left me wondering too 
kyle! you left sanshin in the shadow.
Hey, I can’t put Wikipedia out of business. 
http://en.wikipedia.org/wiki/Sanshin
Seriously though, Sanshin isn’t something I’ve pursued, so I don’t have much to say about it. It uses slightly different positions (unlike tsugaru scale, which is generally minor pentatonic), but the same tuning. As for the music, I would say the sanshin is more meant to be accompanied by a singer, unlike shamisen, where there are a lot of instrumental pieces. But that’s just my opinion. It’s all gooood. 
This is a nice bit of sanshin - http://www.youtube.com/watch?v=HrwdVUnznOo&feature=player_detailpage#t=26s
They’re both Japanese… right?
My aunt had a sanshin from okinawa at one point. Every time there is a sanshin, there is someone usually singing.
nice song you linked Raul.