PLY 3D models store simple geometric data (point clouds, basic meshes with colors), while FBX supports complex dynamic content like animations, rigs, textures, and scene hierarchy.
PLY focuses on static or scan-derived models—common in 3D scanning or scientific visualization—since it only retains vertices, faces, and basic attributes. FBX is a versatile interchange format for animation and game workflows, preserving bone structures, keyframes, and cross-software compatibility (e.g., Blender to Unity).
Use PLY for lightweight static/scanned objects; choose FBX when you need animations or seamless tool integration.