Work is defined when there is a change of volume. Mathematically, $W=-\int P\, dV$. When pressure is constant $W= P\, \Delta V$. For an ideal gas expansion we have $W= nRT\ln\frac{V_2}{V_1}$. If its constant volume then $W=0$ in both cases.
Enthalpy is defined as $H=E+P\, V$, where $E$ is the internal energy. If it is a change with constant volume, $Q=\Delta E$ and $\Delta H=Q+ V\, P$. In this case, what is $V\,\Delta P$? It cant be defined as work since no volume changes. Maybe a form of energy transfer that is not work but similar to it? Does it have particular name? Or can it be included in a kind of works?
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