All leather starts as aniline leather.
All leather is aniline dyed after the tanning process.
The color intensity and pattern of the grain will vary naturally. Different parts of the hide accept dye to different degrees resulting in various hues. Aniline leather is easy to scratch with a fingernail with the affected area going to a lighter color. This type of leather is porous with water and oils absorbing easily. Proper protection limits but does not stop this type of absorption.