NFV or Network Functions Virtualization is an architecture concept which uses virtualization related technologies to virtualize entire classes of network node functions into building blocks that may be connected, or chained, together to create communication services.
SDN or Software Defined Networking abstracts the concept of traditional networking, and places the Control Plane functions on an SDN controller. The SDN controller can be a server running SDN software. So in short SDN orchestration is the ability to program automated behaviors in a network to coordinate the required networking hardware and software elements to support applications and services. SDN can involve NFV for one or more nodes of the network but not necessarily.