What is PLY?
PLY, the Stanford triangle format, came out of 3D scanning, and it shows: it carries per-vertex extras like colour and confidence that most mesh formats have no room for. It exists as ASCII and binary; FileSorcery reads the ASCII form.
What is GLB?
GLB is glTF packed into a single binary file - geometry, materials, textures and a node hierarchy in one blob. It is the format the web actually uses for 3D, and the one most viewers, AR tools and game engines want.