SDN and NFV are siblings but not twins -- while they have a lot in common, they aren't identical. Here's what you need to know about their differences.
"Network functions virtualization and software-defined networking are two closely related technologies that often exist together -- but not always. Broadly, NFV and SDN both use virtualization and automation to facilitate the creation of more nimble, responsive networks, but the two technologies differ in their specific goals and execution.
While both SDN and NFV abstract network intelligence from physical hardware, SDN typically involves doing so across the network as a whole, while NFV deals with virtualizing individual network services..."