In 3D texturing, bump maps and normal maps differ primarily in their method of representing surface detail: bump maps use grayscale values to simulate height changes, while normal maps use RGB color channels to store surface normal directions.
Bump maps create depth illusions by adjusting light reflection based on grayscale intensity—darker areas appear indented, lighter ones raised. They are simpler and lighter, ideal for basic height effects.
Normal maps, however, store surface normal directions in RGB channels, capturing angles to enable more accurate light interactions. This results in more realistic renders, making them preferred for detailed, lifelike surfaces.