What is the difference between PV wire and USE-2 solar wire?

I am thinking about using one of the new transformerless inverters, either the Astronergy / Chint Power inverters or the KACO New Energy inverters and when there is no transformer in the inverter it states that PV wire needs to be used.  How do I know if PV is on my leads from my panel?  How does it differ from USE-2 wire?




The data sheet for your module will state, "PV Wire", specifically. Also, the wire itself will be labelled as such. 
The attached photo shows a spec sheet with the PV wire notation. Interestingly, many manufacturers are asleep at the wheel when it comes to noting the use of PV wire on their own modules. You can also see in the picture, that PV wire is not all rated at 1000Vdc - as many people assume that if wire is rated at 1000Vdc, then it is PV wire...