Though it’s easy to differentiate from the tsugaru shamisen by the size of the itomaki, it looks much more similar to the nagauta shamisen, because the itomaki are more similar. This is the best way to find the difference is looking at the base of the sao (neck), called the Hatomune.

Hatomune (slope at the end of neck)
The hatomune of a jiuta shamisen cuts off sharply, whereas the hatomune of a nagauta shamisen slopes downward.