These two formats are used by two different applications. The PDS belongs to the PowerDirector one, and the VSP to the VideoStudio Pro by Corel.
- You can find info about PowerDirector here
- And for the VideoStudio Pro here.
I recommend using one version of the file and then export to one supported by the other application, then import it and save as the native version of the second application. For example, load the VSP in the original software, export it to one of the formats supported by the VideoStudio PRO and then save it again using the native format supported by VideoStudio Pro.