Despite their similar-sounding names, RGB and A-RGB are two completely different lighting standards that cannot be easily connected.
RGB LEDs are powered by an analogue 12V signal via a 4-pin connector:
The lighting options with "standard" RGB are limited. For example, the LEDs can be reduced in brightness, but only one colour and brightness can be output at a time.
A-RGB, on the other hand, is supplied by a digital 5V signal via a 3-pin connector:
The lighting possibilities with A-RGB are much more advanced than those of RGB. For example, different LEDs of an array (e.g. fans or LED strips) can light up simultaneously in different colours and in this way also create patterns or various stylish effects, such as rainbows and colour flashes.