The AP inks/tones are a bit less viscous than the Citadel ones. A bit subtler too I think. I'm not a regular user of washes, inks and so on, but these Perry WW2 figures are so small and (in the case of the plastics anyhow) so detailed, that they kind of demand it if you want to be able to make out all the lovely little details of pockets, pouches and so on...