How Can you spot the difference between a MK4 VW Golf GT TDI 130bhp and 150 bhp?

[ThineshK]

I am very interested in buying a MK4 Golf GT TDI 150bhp! But what are the differences between a 130bhp and 150bhp?

 

[JosephPero]

Serial number and 20 bhp

 

[DanS]

20 hp diff