Working between Keynote and Powerpoint
From Help Wiki
Powerpoint is installed on all of the Windows and Macintosh machines in the computer center. Another presentation software, Keynote, is installed on all of the Macintosh machines in the center. Both of these programs are easy to use, and can make excellent slideshows.
It can be useful, and is very easy to transition between these two programs.
Powerpoint to Keynote
If you have a Powerpoint presentation that you would like to modify in Keynote, most .ppt files can be opened directly with Keynote, automatically converting them in the process.
Keynote to Powerpoint
If you have a Keynote presentation that you need to run on a Windows computer, this can also be easily done. You can simply export the file as a .ppt (Powerpoint Presentation) from the File menu.