Ive bought a 2003 T4 VW Transporter and on the little green slip off the V5 document which i have it says the 'taxation class' is private/light goods (PLG)

What is the difference between this and lights good vehicle (LGV)?

From what i can see PLG is £245 and LGV £240.

The T4 is a disabled converted with a ramp in the back. I thought it would be classed as a van to which it is (commercial vehicle)