An electric field $\overrightarrow{E}=4x\widehat{i}-\left(y^2+1\right)\widehat{j}N/C$ passes through the box shown in figure. The flux of the electric field through surfaces $ABCD$ and $BCGF$ are marked as ${\varphi }_{\text{I}}$ and ${\varphi }_{\text{II}}$ respectively. The difference between $\left({\varphi }_I-{\varphi }_{II}\right)$ is (in $\mathrm{N}{\mathrm{m}}^2/\mathrm{C}$ ) ____________.