The Ghostwalk Running Man is different from the Slide:
It's that one is a slide in place and the other requires a side slide. A slide requires direction, a Running Man in place does not.
The Running Man in place is done with two feet, whereas the Slide Man is done with the left and right feet doing the main sliding action, and the other foot doing the decorative action while sliding.
Running and sliding in place are one of the basic moves of the Ghost Walk, and both require dancers to be very skillful.
Running in place can be used as a basic movement to start and over move, while sliding can not be used as a starting movement, generally sliding is used for over and main movement.