They are VERY difficult to distinguish, especially in pictures.
Here are some pics of my female from another thread:
Talking to Jeremy at Fire-Ball reptiles, it seems that the head spot, striped tail and overall color are what he sees to pick them out in a clutch. With that said, some folks also look at the belly. There seems to be some variability even in these markings. I would not buy a Specter from someone other than a trusted source, who is producing Super Stripes.