No, VORs are not all the same.
A VOR transmits two signals, both at the same frequency. One is frequency modulated, and the other is amplitude modulated. Because the information that's being transmitted on each of the two carriers is the same frequency, it's possible to do phase comparison of the two signals, and that's exactly what the VOR receiver in the aircraft does to establish what radial it's on.
Traditionally, a VOR would transmit the FM signal in all directions equally. The AM signal would be transmitted in such a way that its phase is different depending on which direction from the transmitter your aircraft is. This was a very simple mechanism, and didn't require much ground equipment. As such, the transmitters are difficult to spot from the air.
The problem with this type of transmitter is that it is particularly susceptible to interferance from obstacles which are located near to it. Some clever b@stard figured out another way of arranging the transmitter. Rather than rotating the AM signal, he fixed the AM signal, and use Doppler shift to rotate the FM signal. The resulting transmitter, the Doppler VOR, is much bigger, and is probably the one that you're familiar with, since all modern VORs are built this way.
As a user of the VOR, you don't really care which method it uses, since the receiver works exactly the same way. I don't know either of the two VORs you mention, but it could be that POL is a very old transmitter, which uses the old technology? Not sure how you could find this out other than find someone who actually knows... does that AIP list the type of transmitter? I'm not sure...
Hope that helps, anyway.
FFF
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