What's the difference between a slalom board and a GS board?

Slalom boards are shorter (155–163cm) with tighter sidecut radii (6–8m) for quick, snappy turns in rapid succession. GS boards are longer (163–175cm) with larger sidecut radii (8.5–11m) for longer, faster, more sweeping turns. GS boards are faster and more stable; slalom boards are quicker and more responsive. For recreational alpine carving, a GS-style board is more common because it's more forgiving and versatile at recreational speeds.