It's so hard to tell. If I had to make a wild guess, it's probably one of the Agristarts varieties, since they are widely available. Maybe Smooth Cayenne. My SC's from Agristarts were not so "Smooth" and had a good amount of spines, but the leaves were all green like yours.
If it had a nursery tag, I'd call them up. The garden center manager at Home Depot could probably also tell you what nursery your plants came from.