Strap-on pads are the most minimal option—they're individual pads that attach directly to your body with elastic bands, covering only the specific areas you want protected. They're lightweight, low-profile, and won't add warmth under your ski pants, which some skiers appreciate on milder days.
However, strap-on pads have a significant downside for skiing: they're the most likely to shift out of place during active movement. When you're carving turns, falling, or even just sitting on the lift, the elastic bands can allow the pads to rotate or slide, leaving your hips exposed exactly when you need protection most. For a sport with as much dynamic movement as skiing, that's a real concern.
If you want reliable hip protection on the slopes, impact shorts or wrap/belt styles are much better choices—they stay put far better. Strap-on pads are really best suited for very light activity or recovery situations where you're mostly walking rather than skiing aggressively.