Yep, mine remains the only Dahon 20" folder with mid-drive.
Dahon do make two mid drives and also a rear hub drive bike. The E-20 has a 200 watt mid drive, and weighs 17 kg. Its likely a Tonsheng mid drive and torque pedal sensing setup. The K-One has either a 250 rear hub Bafang setup and weighs 19kg, or an alternatively the K-One has a mid drive 250 watt Tonsheng torque pedal sensing and weighs 20kg.
E-20 (also referred to as Unio E20) seems to come standard with a rear bike rack and mud guards, and it seems to be fitted with 2 inch wide tyres. While the K-One comes with 1.75" wide tyres (mostly) it seems. And one has to add the mudguards and the rear rack.
The K-one can be fitted with wider tyres but the front mudguard looses clearance and the front of the guard won't fit over a 2.15" front tyre. Both mid drives use a torque sensing motor output technology, whilst the rear drive hub motor uses a cadence sensor ie the motor power is related to pedal rotation and maybe speed of pedal turns (that depends on the software).
Incidentally the wider the tyre, the more air, and hence, the ride can be softened with a wider tyre.
The K-One also has a higher horizontal bar compared to the slanting down horizontal bar on the lighter E-20.
I don't know if the E-20 has alloy or chrome moly front forks. The K-One has chrome moly front forks, while the rest of the frame is alloy - except for the steel cable below the horizontal frame. That cable is referred to as "Deltec" by Dahon, and they claim it is patented. It seems a light weight way to strengthen a bike.