What's the difference between Red and Panang curry?
I have just looked in the book "Thai Food" (by David Thompson).

Both are very similar. The main difference I can see is that there are souring agents in the red curry (fish sauce and shrimp paste). These are absent in the panaeng which has peanuts as a major ingredient in the paste (and nutmeg).

The panaeng is also usually made with beef which is simmered in count milk until tender.