In this note, we solve the open problem posted by Tien and Khoi (Monatsh Math 188:183–193, 2019). We prove that when \(0<q<p<\infty \) , the difference of two weighted composition operators between Fock spaces \(W_{\psi _1,\varphi _1}-W_{\psi _2,\varphi _2}:\mathcal {F}^p\rightarrow \mathcal {F}^q\) is bounded if and only if both \(W_{\psi _1,\varphi _1}\) and \(W_{\psi _2,\varphi _2}\) are bounded. Furthermore, we prove that the same conclusion holds for the differences of a weighted composition operator and a weighted composition-differential operator on \(\mathcal {F}^p\) .