If you look again and compare, there are actually quite a few differences, notably and radiator areas. Granted, it's not as easy as in the past to tell locomotives apart. The SD70 has a very large flared radiator, like they used in models such as the SD80MAC, and a curved roofline over the engine compartment. The ES44, for the most part, looks similar to other GEs, but the radiator area is longer than earlier models. Hope this helps.