Let $Z_1,Z_2,Z_3,Z_4$ be distinct complex numbers satisfying $\left|Z_1\right|$=$\left|Z_2\right|$=$\left|Z_3\right|$=$\left|Z_4\right|$=1  such that, 

0$\le$$\arg \left(Z_1\right)$$<$$\arg \left(Z_2\right)$$<$$\arg \left(Z_3\right)$$<$$\arg \left(Z_4\right)$ and

$\arg \left(Z_2\right)+\arg \left(Z_4\right)-\arg \left(Z_1\right)-\arg \left(Z_3\right)=\pi$

then the value of 

${|Z_1{Z}_3-(Z_1-Z_3)(Z_2-Z_4)|}^2-{\left|(Z_1-Z_3)(Z_2-Z_4)\right|}^2$ is