Pixel Dimming dimming technology for OLED displays, LG. LG used Pixel Dimming at first, but then Pixel Level Dimming appeared on some TV models.
Pixel Level Dimming vs Pixel Dimming, these are different names for the same technology, there is no difference between them.
If the LED dimming the screen comes off the backlight LEDs darken only large areas, to get a true black color is not possible, an OLED display, each pixel emits light itself, because of this, you can disable any pixel and to get really deep black color.
Similar technology is used in quantum dot displays QLED displays (SUHD TVs from Samsung).