I will be covering the different types of mapping available when modelling. Bump maps can create detail in the model that is actually fake. It doesn’t add any additional resolution to the model as bump maps are grayscale images that are limited to 8-bits of colour information. The values in a bump map are used to tell the 3D modelling software up or down. If the values are close to 50% grey then there’s little to no detail that will show through on the surface. Turning the colour closer to white will make the details appear to be pulling out of the surface whereas turning it closer to black will do the opposite and make then appear to be pushing in. Wrinkles and pores are some examples of what bump mapping can be used to create. Bump mapping can be rather easy to create and edit in a 2D application such as Photoshop or Illustrator, however, bump maps can break if the camera views it at the wrong angle due to the detail being fake. The silhouette of the geometry that the bump map is applied to will remain unaffected the map.
Normal maps can be referred as a better type of bump since it has essentially replaced it. like bump maps, the detail that they create is also fake. However, unlike a bump map, normal maps use RGB information that corresponds directly with the X, Y and Z axis as the information tells the application the exact direction that the surface normals are oriented in for every polygon. The orientation also tells the application how the polygon should be shaded. Normal maps can be rather difficult to create or edit within a 2D application such as Photoshop so a likely option would be to bake a normal map using a higher resolution model.
Displacement maps are king when it comes to creating additional detail for low-resolution meshes. In order for detail to be created based on a displacement map, the mesh must be subdivided or tessellated so real geometry is created. Displacement maps can be painted by hand or baked from a high resolution model and it consists of greyscale values like bump maps. 8-bit displacements are available although they aren’t the best option as using 16 or 18-bit will provide a better result since 8-bit displacements may look good in a 2D space but can sometimes cause banding or other artifacts when they are in 3D due to insufficient range in value.
Source of information: https://www.pluralsight.com/blog/film-games/bump-normal-and-displacement-maps.