Convert md3 to x

What is the difference between .md3 and .x?

Description: MD3 (Quake 3 Model) is a 3D file format used by the game engine in the Quake 3 Arena video game. It is used for storing 3D models of objects and characters and is composed of several different sections that store the geometry, animation, and textures of the model.; X is a DirectX Model image file used by DirectX technology which is for 3D graphics rendering in games. The file format specifies 3D object structures for meshes, textures, animations, and objects.