Fixed-lens goggles have a lens that's permanently attached, so you can't swap it out when conditions change. They're typically the most affordable option and work well if you ski or ride in fairly consistent weather—like sunny resort days or predictable spring conditions.
The downside is zero adaptability. If a bluebird morning turns into a flat-light storm afternoon, you're stuck with whatever lens you started with. That can mean squinting through glare or struggling to read terrain in low visibility. Some riders solve this by owning two pairs with different lens tints, but that can cost more than one interchangeable goggle.
Fixed goggles make the most sense for budget-conscious riders who stick to predictable conditions or only get out a few times a season. Just make sure to pick a lens tint that matches your most common weather—usually a versatile all-around tint rather than something extreme.