.amf
AMF modelAdditive Manufacturing File Format
An XML format for 3D printing, published by ASTM in 2011 and later adopted by ISO. It adds curved triangles, colours, materials and lattices to the plain mesh idea of STL.
Multi-material and colour 3D prints in slicers that support it.
Opens in PrusaSlicer, Slic3r
About AMF files.gltf
glTF modelGL Transmission Format
An open 3D format from the Khronos Group, first released in 2015. A JSON file describes the scene and points to separate binary buffers and texture images.
Exchanging real-time 3D scenes with materials and animation between tools and engines.
Opens in Blender, three.js, Godot, Unity and Unreal (with plug-ins)
About GLTF files