I got a 1600 receiver unit, and its .pdf file mentions "WAAS/e-Dif".  {note: the 1600 unit replaced the 1500 unit}

link:

https://knowledgebase.agleader.com/kbp/index.php?View=entry&EntryID=927&mobile=0

I've been pretty happy with it on row clutches and spraying (after I do initial perimeter with AutoSwath  "OFF") I don't have AutoSteer.

I wonder if this "e-Dif" has helped improved the correction signal or its just a better/improved algorithm; like gpsdude mentioned.