I'm able to factor this kind of equations (x+y)^{2}-(x-y)^{2 }but 4 og -9 makes it difficult.
Write it as $\displaystyle \displaystyle \begin{align*} \left[ 2\left(x + 3y\right)^2 \right] - \left[ 3\left(2x - y\right)^2\right] \end{align*}$ then apply the Difference of Two Squares.