The web site doesn't specifically say...but I assume that Kies is for Android based devices, NPS and PCStudio are for W7p and other Phone OSs?
New PC Studio is for Samsung's proprietary OS1. I believe PC Studio 3.1 is just an older or region-specific version of NPS.
RoToRa is correct that Kies is for both Bada and Android. It appears they are transitioning to using "Kies Mini" for Android, which is really just a means of updating the device software. Media management, sync, etc. is intended to be done through the "cloud" on Android devices.
After looking at the Samsing website, I believe they do not have management software for their Windows Phone 7 devices.