hi
What is the difference between ( vertex paint and texture paint ) >?
Texture paint - paints to an image texture file mapped to the object UVs http://www.blender.org/manual/painting/texture_paint/index.html?highlight=texture%20paint
Vertex paint - adds colour to the vertices. It does not use an image or any UVs. Vertex paint can be baked to an image texture. http://www.blender.org/manual/painting/vertex_paint/index.html?highlight=vertex%20paint
Can I use both in the same modeling or mesh
Sure, you can. If you’re dealing with Cycles, you import painted texture (raster image) with Texture->Image node. To access Vertex Paint you should put its exact name into a Input->Attribute node