For Face ID uses Apple the TrueDepth camera on the iPhone X for face recognition. Among other things, she scans up to 30,000 points on her own face. This "map" of your face is stored in the Secure Enclave and never leaves your device.
Snapchat Uses TrueDepth Camera
However, Apple allows developers at least access to copies of face maps which recognizes as many as 52 microexpressions on the eyes, lips and face.
This is exactly what Snapchat has taken advantage of for the first time. Because since today you will find some new masks that are specially designed for this purpose. Immediately upon use, you can see that they are much better and move along with your facial features. For example, today you can breathe life into a colorful wrestler mask or hide behind a porcelain head. There is also a mask that reminds a little of a Venetian mask. These three are currently the first to make use of TrueDepth camera capabilities. It probably will not be the last.
What lasts long ...
The question is, why are these new masks in Snapchat only now appearing? Because Apple already announced at last year's event in September 2017. So it took almost half a year (the iPhone X was released in November) before the feature actually comes into effect.