What is the difference we hear you ask; so let’s answer that question first.
Bi-Fold shutters use hinges to fix all the shutter panels together, so if you want them folded back completely, they will concertina alongside each other and sit neatly against either side of the window or room, still looking gorgeous. SGS Shutters and Blinds also make a free-floating version which you can discuss with your installer.
Bi-Pass shutters are not hinged together but sit in gliders which then allow them to slide in front or behind each other. This type is extremely popular for use as room dividers and for wardrobe doors.