Active ventilation goggles have a small built-in fan that constantly circulates air to prevent fogging. For most resort skiers, this is more than you need—enhanced passive ventilation does a great job without the extra cost and weight.
However, active ventilation is genuinely worth it if you're a heavy sweater, wear prescription glasses under your goggles, or spend long days skinning up in the backcountry where exertion and humidity are high. It's also a lifesaver in extremely wet, coastal snow climates where fog is relentless.
The trade-offs are real: these goggles cost more, weigh a bit more, and you'll need to keep the battery charged. If the fan dies mid-day, you're stuck with standard airflow until you can recharge. But if fogging has been a chronic problem for you, powered ventilation is the most effective solution available.