The horizontal doors used on closet sliding doors move along a track mounted overhead and a floor guide for stability. To manage the smooth movement they‘ll have cushions and buffers on the ends to prevent damaging adjacent construction to ensure a smooth gliding motion when operated. Closet sliding doors of the vertical variety are seated in a groove, much like dresser drawers to ensure they glide in one direction.
When you are looking at the front door designs keep in mind the rest of your house. If you have a specific style throughout the house you should try to have the front door design match. It would detract from the style that you have already worked so hard to create in your home if you choose a door that clashes with this style.
Closet door manufactures are becoming more in tune with the desires of the homeowner. Glass closet sliding doors can be controlled with top mounted hardware to help the user control track and hardware problems that seem to be a major concern with floor track mounted systems. The building industry has embraced this concept to the point that entire home designs are built around these concepts.