I would like you to define some words.
Model - does it consist of just one mesh? Or multiple meshes?
Mesh - does it contain multiple objects. I mean should the mesh contain more than one pair of index/vertex buffers for example.
Node - It may be scene node, and it contain pointer to the mesh/model?, the texture, shader, etc.(to allow using the same mesh with different textures). It contain also parent(if the scene is tree oriented), relative position, etc..
Where does the animation goes to? There are thousands of ways that come to my mind to handle animation. Is the character represented from long list of verticles(just one buffer)? If so, I guess animation would go into the mesh object.
These questions may seem easy to answer by some people but I would like to make the things clear for myself.
There may be different interpretations of the words I mentions, but what do you understand/imagine when you see these words.