The unlocked version technically supports Verizon's network fully. But Verizon may still refuse to activate it since they didn't sell it. I suppose the result is the same for the customer, but that's the more detailed answer.
"Switch to Verizon and save: If you’re switching to Verizon from another carrier, you can receive up to $650 to pay off your old phone or contract when you trade in your current phone. Visit a Verizon store to have your... (continues)