If you did RTFA, on the first page you'd see:
"Switching from the backlit mode, to the reflective one drops the display's power consumption from 2.5 Watts to 0.5 Watts. This is for a refresh rate of 60 Hz--fast enough to display video. Pixel Qi claims that using software to put the display into an e-reader mode--suitable for reading text, where the screen might only update ten times a second--could drop the power consumption to as low as 100 milliwatts."
For the IMOD:
"The height of the air gap between the plates determines the color of light that is reflected from the IMOD. When a voltage is applied, the plates are drawn together by electrostatic forces and the element goes black. When the voltage is removed, the plates separate and color is reflected off the IMOD. A single pixel is made up of several IMODs; adjusting the height of each affects the overall color of the pixel. The plates stay in place, using almost no energy, until the color needs to change again. A plate only has to move a few hundred nanometers to change color and can do it in tens of microseconds--fast enough to show video."
"The LCD devices are based on a technique called electrowetting, in which a voltage is used to modify the surface tension of colored oil on a solid substrate. In the absence of a voltage, the oil forms a film over the substrate and is visible to the viewer. When a voltage is applied, the pixel becomes transparent. By controlling the voltage of each pixel independently, a picture can be displayed. Unlike E Ink's technology, electrowetting pixels can be switched in a few milliseconds, making them suitable for showing video."
What the article doesn't say, which is easiest on the eyes. My bets are still on e-ink.
Recently I tried this "Libre" LCD-based e-reader, and my eyes were bleeding, it was that horrible, or maybe I'm spoiled by real e-ink, and no, it's not Kindle.