Elastic gaiters are the most common style you'll find on snow pants—they're simple built-in cuffs at the bottom of each leg that stretch over your boots to keep snow out. For most resort riders, they work just fine. They create a decent seal that blocks snow from sneaking into your boots on typical ski days.
The tradeoff is that elastic can lose its stretch over time, especially with frequent use. They also don't let you customize how tight the seal is, which matters if your boots are on the smaller or larger side. Adjustable gaiters with snaps or hooks give you a more secure, longer-lasting fit—handy if you regularly ride deep powder.
If you're mostly sticking to groomed runs at the resort and want to keep things simple and lightweight, elastic gaiters are a solid, budget-friendly choice. Just check that they fit snugly over your specific boots before you buy.