Customers sometimes ask me, what the Difference between a POC and a Pilot is. I found this nice Sheet (but had to modify it / tweak it since it did not reflect correctly in my Opinion)

Although a Pilot is very near the Production I personally would never purchase licenses before I checked, that the Pilot works flawlessly. I think one of the biggest Core-Differences is, that a Poc is on Vendor-near Hardware in the Lab and the Pilot is happening in your Live-Infrastructure with the final Vendor Hardware and Config.