OBJ vs GLB: the old interchange format meets the modern one
OBJ carries geometry and UVs but no PBR materials; GLB carries a full scene with physically based shading. Which to pick depends on where the mesh is going.
What OBJ actually holds
OBJ is a text format from the early 90s: vertex positions, normals, UV coordinates and face lists, plus an optional .mtl sidecar describing basic colors and texture filenames. It predates physically based rendering, so there is no way to express metalness, roughness maps, or clearcoat.
That makes OBJ an excellent geometry shuttle and a poor material shuttle.
What GLB adds
GLB wraps the glTF 2.0 spec: binary buffers for geometry, plus a material model built around PBR — base color, metallic, roughness, normal, occlusion and emissive channels, with extensions for clearcoat, transmission and iridescence. A logo exported as GLB keeps the exact material it was shaded with.
Choosing by destination
Sending to a web viewer, a game engine, or another modern tool: GLB. Sending to a legacy CAD tool, a sculpting package that only imports OBJ, or a pipeline that re-paints meshes anyway: OBJ.
Converting GLB → OBJ drops PBR parameters by design — geometry and UVs survive, materials revert to simple colors. Converting OBJ → GLB wraps the geometry in a default material you can then re-style in the editor.