(A) : Vander Waals equation is applicable to non-ideal gases.
(R) : Ideal gases obeys the equation PV = nRT

Van der Waals’ Equation of state for a real gas:

$\left(\mathrm{P}+\frac{{\mathrm{an}}^2}{{\mathrm{V}}^2}\right)\left(\mathrm{V}-\mathrm{nb}\right)=\mathrm{nRT}$
This equation can be derived by considering a real gas and 'converting ' it to an ideal gas.

The equation, $\mathrm{PV}=\mathrm{nRT}$ is an ideal gas equation and is applicable only to an ideal gas.

So, both A and R are true but, R is not the correct explanation of A.