$PV=nRT$ is the standard form of the ideal gas law, where:

• $P$ = pressure

• $V$ = volume

• $n$ = number of moles

• $R$ = gas constant

• $T$ = temperature (in Kelvin)

$PV=dRT$ is a derived form of the ideal gas equation when you use density $d$ instead of moles $n$ (using $n = frac{dV}{M}$, where $M$ is molar mass).