that the Great is richer in orange and black contrast color on top compared with the paler and less black on top. However the underside is just the opposite in rich color for the Gulf variety which has silver on the front and back wings were the Great has it only on the back wings. I also noticed the primary diet of the Greater is Violets and the Gulf diet is Passion Flower. The Greater is also about a 1/4" wider wing spread on the average. This is the site I use to check butterflies and moths. https://www.butterfliesandmoths.org/ If I was an environmentalist that argues the bright colors are to ward off predators then I would argue the Great Spangled Fritillary spends its time sitting aright on top of flowers while the Gulf Fritillary hangs upside down from the flower. But on our plants it seems to be 50/50.