Cr. sp. "Atabapo I" will be the reddest of the Atabapo pikes. It is also less common. When young they have the classic Lugubris group pattern and shape. Beige body, head to tail horizontal mid body stripe & lightly spotted face. These are a little bit older and are showing some color but you get the idea.
When mature these are probably the reddest pike known.
Cr. sp. "Atabapo II" also known as the "fire pike" ot "ladder pike" is not nearly as red when mature. Juveniles have a very distintive pattern of vertical body stripes that cover only the top half of the body. There's no mistaking these for any other pike.
These used to be quite rare but seem to be the most often imported large pike right now with the exceptions of
Cr. lenticulata and
Cr. sp. "Venezuela"
Pictures of adult Atabapo II are few and far between for whatever reason. This is the best I can find.
Here's a shot of two adults from each specie showing the differences. Both fish are stressed and not looking their best but it helps.
Hope that helps.