The NOE was the first Natural Outlaw. It has the Ergo handle which is the handle that replaced the Busse straight handle. The latest version of the Natural Outlaw is the Special Forces Natural Outlaw. Special Forces refers to the handle shape. The SFNO is hard to find and has a larger blade than the NOE. The NOE is easier to find and cheaper.
There is a knife called a SOW that is a variant of the SFNO. They cost a little more than an SFNO but they are easier to find, they are a custom shop product, full flat ground with a slight recurve and satin finished but otherwise very similar to the SFNO.