Bump Maps :
You can use a bitmap file or procedural as a Bump map, which makes an object appear to have a bumpy or irregular surface. (Grayscale) white raised, black is opposite.
Displacement Maps :
Displacement map actually changes the geometry of the surface and the lighter colours in the 2D image push outward more strongly than darker colours, resulting in a 3D displacement of the geometry. (Grayscale)
Normal Maps :
Normal bump mapping is a way of adding high-resolution detail to low-polygon objects. It is especially useful for real-time display devices such as game engines, and it can also be used in rendered scenes and animations. A normal map is a three-color map, unlike the grayscale maps used for regular bump mapping.