How are you saying they are the same? One is from Africa the other is from the Middle East and dry areas of Asia. That's like saying crested geckos and day geckos are the same because they can both live in Exo-Terra enclosures and can eat meal replacement diets. They are vastly different from one another. A lot of people mix them up from seeing pictures of them, once you look at a few you will notice big differences. Leopard geckos have more a bull dog head fatties have a round face with big doe eyes. Fatties are just chunkier all around, leos are lean; fatties have much smaller feet as well. Leopard geckos are much more active requiring slightly larger enclosures; fat tails are almost always hiding in the same spot in their tubs. They are very similar to ball pythons (they come from the same region) hiding all the time in small burrows. Even the base morphs are completely different. I'm not a fan of albino leopards but amel fat tails are stunning, there are many affordable morphs to work with in the fat tail world to produce awesome combos or more base morphs, amels, carmels, granites, whiteouts, caramels, zeros, white socks, and various hets. Their personalities are like day and night between the two. Handle multiple animals from each species and you will notice these differences in no time.
I also hate crickets and gave up on geckos many years ago until I discovered how easy roaches were to breed. Dubia and lateralis are amazing feeders with little care. I'd highly recommend feeding these prey items over crickets. Since roaches are mostly herbivores you don't have to worry about them munching on your geckos if you let your prey free roam in their setups like you would with crickets.