Viewing the AGRussell website, I see there's a difference in the rod angles between the two. The Sharpmaker offers two angles (30 or 40 edge-to-edge), and the Field Sharpener has one (30 degrees edge to edge). Note that the narrator of the AGRussell Ceramic Sharpener (the wood base and ceramic rod one) says that "We have always disagreed with Louis (Graves) about the proper angle for the rods", and that the Field Sharpener is also "Based on the work of inventor Louis Graves." I could interpret this all as an endorsement of the Sharpmaker over the AGRussell sharpeners, from their own online catalog. Maybe I'm reading too much into it, though. I'm getting a Sharpmaker soon, myself.