GLB and USDZ are both single-file 3D formats that carry geometry and textures, but they serve different homes: GLB is the open standard for the web and game engines, while USDZ is Apple's format for AR Quick Look on iPhone, iPad, and Vision Pro. If you are unsure, export both, which 3D Mate does from one photo in a click.
GLB is binary glTF, an open Khronos standard. It loads in browsers (three.js, model-viewer), and imports cleanly into Unity, Unreal, Godot, and Blender. If your model is going into a site, an app, or a game, GLB is the answer. See game assets.
USDZ is based on Pixar's Universal Scene Description, packaged for Apple's AR Quick Look. Tap a USDZ on an iPhone and it drops into your room in AR, no app needed. It is the right format for AR on Apple devices. See what is a USDZ file and augmented reality.
Web or game engine: GLB. Apple AR: USDZ. 3D Mate generates a model from your photo on your Mac and exports both (plus OBJ, STL, PLY, and 3MF), so you are covered wherever the model goes. Formats overview: 3D file formats explained.