To add texture to a material you can use 3 different kinds of maps, Bump, Displacement and Normal. Each works based on their own colour ranges. Each map can be affected by scale to change the intensity of the map.
Bump maps create the illusion of depth and texture on the surface of a 3D model using computer graphics. Textures are artificially created on the surface of objects using grayscale and simple lighting tricks, rather than having to manually create individual bumps and cracks. No additional resolution is added to the model as a result of a bump map. Typically, bump maps are grayscale images that are limited to 8-bits of colour information. That’s only 256 different colours of black, grey or white.
Normal maps can be referred to like a newer, better type of bump map. As with bump maps, the first thing you need to understand about normal maps is that the detail they create is also fake. There’s no additional resolution added to the geometry in your scene. In the end, a normal map does create the illusion of depth detail on the surface of a model but it does it differently than a bump map. As we already know, a bump map uses grayscale values to provide either up or down information. A normal map uses RGB information that corresponds directly with the X, Y and Z axis in 3D space. This RGB information tells the 3D application the exact direction of the surface normals are oriented in for each and every polygon.
Displacement maps physically displace (as the name implies) the mesh to which they are applied. In order for detail to be created based on a displacement map, the mesh must be subdivided or tessellated so real geometry is created. The great thing about displacement maps is that they can actually be either baked from a high-resolution model or painted by hand. Like a bump map, a displacement map consists of grayscale values