The only major difference is the fact that OLEDs are being used as the 'backlight'. Of course the Blue in the colours we see will be the Blue directly from the OLED as it should pass straight through the QD layer. It is 'superior' because like OLEDs, you have each individual pixel that is self emitting and so you get all the benefits you expect with OLEDs - the perfect Blacks, infinite contrast etc. The single 'Blue' OLED pixels are still just responsible for the luminosity/brightness - as a backlight is. The QD layer on the front is responsible for the colour. Its allowing as much of the blue energy through as needed or converting some to red and or green. A Pure blue (no red or green) would pass through, a pure Red would take the blue light energy and change it to pure Red - a white would let a third of the blue pass through, convert a third to green and a third to red. The OLED would essentially just be working on the luminosity of a picture - a 100nit red for example would be a lit 100nit blue on the OLED and the QD layer would change that blue to red.
The same principal can be applied with LEDs too - just use Blue backlight LEDs but you would still have the issue of light bleed etc. The QD layer at the front will allow for 'OLED' like viewing angles and like the system above, can just allow the Blue light through and convert the blue light to Red and/or Green as per the OLED system above. The backlight is still responsible for the illumination/luminosity of the picture - the QD layer would determine the colour by letting that blue pass through and/or converting it to the right amount of Red and Green as required.
MicroLED TV's could also work in exactly the same was as the OLED QD TV - instead of making each pixel be a red, green and blue LED, they just make them Blue and use this as the luminosity layer with the QD on the front to deliver the colour.
All TV's use RGB format and all the colours are created by varying the degree of red, blue and green. What this system is doing, is using the Blue light as the luminosity AND as any of the 'Blue' that colours are made of. Any colour that has no blue on it, will still be lit with the OLED QD layer bit the blue light will be converted to Red and/or green. With current OLEDs, only the Red, Green and/or White sub pixel would be illuminated. To change the luminosity of a Pixel on a QD OLED, you vary the brightness of the Blue pixel - just like you would do with Backlight LEDs. Take the QD layer off and you would have the luminosity of the image illustrated in just 'Blue' lights - the brighter areas are 'brighter' like turning up the dimming switch on your lightbulb.
LEDs are far less accurate because they have to consider the luminosity in zones and use filters to block light getting through where it shouldn't. Take off the QD layer and you would see more of a pixelated look at the luminosity of that picture where as OLEDs could still show 'detail' and shapes - A tree silhouetted against the sun for example because each 'pixel' can have its luminosity perfectly shown where as the LED would be more an average of that zones APL so won't show the darker tree shape. MicroLED TV's too would have the same advantage as OLEDs in this.
Essentially OLED and MicroLED QD TV's are like an LED TV with each pixel having its own backlight. Instead of using a white light to illuminate the pixel and filtering out the red, green and/or blue, they use Blue light and convert none/some/all of that light to red/green as is required to form the colour. The OLED part is just an OLED panel - which has already been relatively easy to manufacture on a commercial level but without the red/green and white sub-pixels - thus making it theoretically cheaper to manufacture because you are not needing 4 sup-pixels for every one of the 8.3m pixels in a 4k screen. It may even make 8k (and 4k OLEDs) able to be made much smaller too. You could make a 4k TV a quarter of the size in OLED because you only need the blue sub-pixel.
Of course an OLED QD, like a MicroLED QD isn't a 'true' emissive panel as the image you are seeing is NOT the image that is being generated at the OLED or MicroLED in this - not unless you want an image that is all 'blue' (apart from the black where the pixel is off) and only representing the luminosity of the picture. The OLED in this only has Blue pixels - its the QD layer in front that is adding the colour. A 100nit blue, white, green and red pixel will look exactly the same as every other 100nit pixels at the OLED - the QD layer will be where the image becomes an image by converting some of that blue into the other colours. A true emissive panel is one that generates the whole image, both luminosity and colours that we see - whether it has an anti-reflective layer on top or not, the image is still being generated and emitted but with this, the only thing the OLED is doing is generating the luminosity of each pixel but the image is being created by the QD layer as its there that the blue light is converted in to the colours. At most, its only a third self emitting as only the 'blue' light is passing through the QD layer without being converted. White, as you may know, is made up of Red, Green and Blue light so only a third of that 'blue' from the OLED panel is being seen by you, the other 2/3rds has been converted from the Blue from the OLED into red and green.
Its superior to LED's because it has 8.3m dimming zones, each pixel has its own 'backlight' and each pixel can be perfectly black. Its superior to 'OLEDs' too despite the fact that the image is not being created at the OLED because it can have a much greater colour volume.
As this shows, the OLED is just Blue and you don't watch TV with just Blue - the QD layer is wher the image is created by taking the Blue light and converting some to red or green and letting the 'blue' pass through. Its the QD layer that effectively creates the image as images are more than just 'blue' and the OLED is just a Full array backlight with each pixel having its own backlight. Without that QD layer, you just have an OLED that is showing the luminosity of the picture in blue only.