Looking back at the original post, I guess this was intended to be for both newbies and experienced growers. But there isn't really a simple way to tell the differences that you can explain to new growers, beyond the obvious differences in the leaves, growth habit, etc. When you're looking at flowers, there is so much variation in the genera that anyone who is not familiar with them will get them mixed up. That's because they all share basic floral charcteristics. That's why all were originally placed in Cypripedium. It wasn't until botanists started really looking at them that they were reclassified.