LEDs with built-in resistors vs 12v leds
AFAIK there is no,  or at least no common, led diode that is typically 12V forward voltage by it self. 12V led are modules that consist of some combination of diodes and resistors to make them suitable for 12V power applications without needing extra current limiting. This may be a single led with resistor, or multiple LEDs with resistor, or maybe a constant current IC. Some may have extra features like reverse protection or any direction input.

But they are not bare diodes.