https://buy.garmin.com/us-us/us/p/560327

Until they're actually out in the wild anything said here will just be speculation.
My guess is that the F5/5X with more pixels on the same size display will be more crisp and the added colors could make for better contrast especially if the white is whiter. The F5S has the same number of pixels but on a slightly smaller display (1.1" F5S vs 1.2" F3) so maybe a tad more crisp but I can't tell from the specs whether it also has the larger color palette or not.
The screen technology will almost certainly be transflective MIP like the F3, F3HR & Chronos, only with the colour count of the Chronos.
The power consumption of this technology is very low. The reflective nature of the display means that the contrast improves as more ambient light is falling on it, only when the ambient light is low is a back light required (the complete opposite back lit screen technologies like TFT). The Memory In Pixel (MIP) means that once a pixel set it is held.
While this technology doesn't have the vibrancy of TFT/OLED etc, I personally think it is the right choice for this sort of product for the extended battery life.