Not sure if this helps for future reference but it works pretty darn well for me;
The way I can tell camel shrimp apart from pepps is the color PATTERN, I know that they can look similar and aside from the pronounced hump shape on the tail of the camel shrimp I found that if you look straight down (sort of a bird's eye view of the shrimp) you can see red bands running horizontally across the pepp's tail, this pattern is something that isn't there on camel shrimp, instead the camel has lines which tend to appear more random.
You can see this in the photo John posted, distinct bands across the shrimp's tail even on the little guy who's lost his color just and it's a little less obvious but I still see the distinct pattern there...
I also second the notion that this lighter colored shrimp is just a scared or stressed little fella, I've picked them up before and they were nice & bright before netting then once I get home open the container and everyone's gone transparent. After a couple of hours in the DT and once they find places to hide, bright color again. My best guess is this is defensive behavior because once they take on this transparent color they are very hard to see against rocks (they just blend in) so perhaps it's completely normal behavior since I haven't seen it happen in DT where they are comfortable and have no predators.
I absolutely love peppermint shrimp and have developed quite the interest in them
I wish I could have more time for this hobby as I would absolutely love to attempt to breed these little guys, for fun...