Yeah that's an odd one. It's neither. Looks to me like an early prototype (or a knock-off) of the RadWagon.
Why it's not (quite) a RadWagon: the down tube is a different shape, grips are a different color, tires are not stock RadWagon tires, running board is a different shape, battery pack shown is a shark pack, but the wagon uses a dolphin pack, the rear pannier blocking tubes are slightly different than the wagon. Much of the rest of it is identical though (I own one).
Why it's not an elMundo: if you compare carefully, nearly every component is a non-match for the elMundo: brakes, seat, handlebars, battery pack, pedals, even the frame is different in a number of ways.
Bottom line: this is either a knock-off of the Wagon, or an early version. One way to know which it's closer to if you're not convinced would be to measure the wheelbase. The elMundo is longer than the Wagon, I think by about 6". If they're selling it for "under 1500", meaning, possibly, 1400, then yes you save $200 over the Wagon, but you're getting an unknown quantity with no warranty.
Will be curious to know what you think/do.