I believe miniLED was a marketing term intended to mislead customers into thinking it was similar technology to OLED. Since most consumers don’t even know what LEDs are, it probably worked.
LCD displays have, for some time now, had LED behind them. Said LEDs produce the white light needed to display the image produced by the LCD panel. MiniLED just provides groupings of the LED panel so that they can be individually turned off to produce darker darks.
Yes, that's what I thought too, but as beefcat said, I conflated Mini and Micro; MicroLEDs seem be non-OLEDs, so to speak. I hope I understood that part correctly!
Micro LED screens are just trying to be like OLED but shittier. Micro LED has lighting "zones" behind the pixels, which is supposed to only light up the area where the pixels are actively being used, (i.e. not totally black) but it often leads to "blooming", which affects even expensive ass devices like the 5th gen 12.9" iPad Pro.
"microLED, also known as micro-LED, mLED or μLED is an emerging flat-panel display technology consisting of arrays of microscopic LEDs forming the individual pixel elements."