I think they are very much complimentary. This vastly oversimplifies things, but you can can almost think of gltf is to USD like PNG is to a Photoshop file. gl

I think they are very much complimentary. This vastly oversimplifies things, but you can can almost think of gltf is to USD like PNG is to a Photoshop file. gltf is meant to be a 3D publishing format, whereas USD is meant to be an asset interchange format between DCC applications. gltf is very minimal in the amount of runtime processing required to interpret and display it (much of gltf can more or less be directly mapped into GL buffers), whereas USD includes an extremely powerful schema and composition system that is highly expressive but much more complex to interpret in its fullest form (meant for sending entire editable scenegraphs between, say, Maya and Houdini and Blender and Presto). Both formats are really great at what they’re meant to do. I was somewhat surprised that Apple picked USD as the basis for their AR stuff, since gltf would have seen like a more natural fit. Maybe the fact that USD has taken the animation/VFX world by storm (many studios are shifting from proprietary internal interchange formats to USD en masse) helped Apple pick.