A Vertex Array Object (VAO) is an object which contains one or more Vertex Buffer Objects and is designed to store the information for a complete rendered object. In our example this is a diamond consisting of four vertices as well as a color for each vertex.
A Vertex Buffer Object (VBO) is a memory buffer in the high speed memory of your video card designed to hold information about vertices. In our example we have two VBOs, one that describes the coordinates of our vertices and another that describes the color associated with each vertex. VBOs can also store information such as normals, texcoords, indicies, etc.