Twist-lock poles use an internal expanding wedge that tightens when you rotate the shaft sections—they have a clean, streamlined look with no external hardware. They're typically found on budget-friendly adjustable poles and some trekking poles that get repurposed for skiing.
The downside is that twist locks can be frustrating on the mountain. They're harder to adjust with gloves on, and in cold, wet conditions, moisture can freeze inside the mechanism, making it stick or slip. They can also collapse unexpectedly if worn or over-tightened, which is the last thing you want when you're relying on your pole for balance.
If you're just cruising groomers occasionally or using poles for light snowshoeing, twist locks can work fine for the price. But for regular skiing—especially backcountry touring—external clamp-style mechanisms (like Flicklock) are far more reliable and easier to operate with cold, gloved hands.