Specifically GIMPShop is a version of the GIMP that has been edited to be more user-friendly for Photoshop users.

The terminology and menu structure are adapted to look and feel more like Photoshop, and other adjustments were also made to make the GIMP more usable.

In the Windows version, the Deweirdifyer Plugin has been used to place all of the various windows into one nesting window, so it will act more like a single program that multiple little programs..

Also the menu structure and terminology are adapted to to look and feel more like Photoshop.

NOTE: To make the Photoshop shortcuts work you have to start GIMPshop once (to create the .gimp-2.2 user dir). Then close it and run the pskeys.bat from the install dir or run the link in the startmenu group.