Provider vDC provides resources to organization vDCs.Provider vDC's resource pools must come from the same vCenter(spanning of provider vDC across multiple DRS clusters is also possible).A single organization can have multiple organization vDCs.Hopefully attached diagram will give you precise information.
Thank you for you quick answer.
If I got it correct
Am i correct?
You are correct ,we wont be able to create VM's in Provider VDC.You need to create Org-VDC,allocate compute resource and create Vapps for VM usage.
Yes,those terms are from business perspective,there are no such alias by default in VCD.