What's the difference between VRPlugin and OpenVR

I am a green hand at VR in Paraview, and I want to know what’s the difference between VRPlugin and OpenVR in Paraview? And what’s the relationship between them? Can anybody kindly explain for me? Thank you very much!

VRPlugin : A ill named plugin that let you connect to a VRPN server for interaction

OpenVRPlugin : A plugin for showing a paraview scene in a OpenVR compatible VR headset live HTC Vive or NVIDIA Index.