Invisible is the type of zipper, Separating is the function.
Separating is also called open or open bottom or open ended. The bottom is finished with a box & pin to allow it to come apart. These zippers have a movable box to facilitate the installation process.
A Separating INVISIBLE zipper is very rare. I stock them in a #4 or 4mm medium weight invisible on mesh or knitted tape for use in bike jerseys, blouses, evening apparel, and as a #6 or 6mm on heavy twill tape for use in costumes and jackets.