The ANGLE_instanced_arrays.drawArraysInstancedANGLE() method of the WebGL API renders primitives from array data like the gl.drawArrays() method. In addition, it can execute multiple instances of the range of elements.
The ANGLE_instanced_arrays.drawElementsInstancedANGLE() method of the WebGL API renders primitives from array data like the gl.drawElements() method. In addition, it can execute multiple instances of a set of elements.
The ANGLE_instanced_arrays.vertexAttribDivisorANGLE() method of the WebGL API  modifies the rate at which generic vertex attributes advance when rendering multiple instances of primitives with ext.drawArraysInstancedANGLE() and ext.drawElementsInstancedANGLE().