I translate RGB LED as being shorthand for RGB LED with controller especially when they are talking about them as on a LED strip.
Then you are missing something big.
Their are four major types:-
1) Four connections, one positive and one for each of the grounds for R,G and B. Normally these are 12V and are controlled by a PWM signal driving a FET in each colour line. This is how you use them
https://learn.adafruit.com/rgb-led-strips/usage. What ever is the colour all the LEDs on that strip have the same colour.
2) Three connections 12V - Every three LEDs have full independent colour control.
3) Three connections 5V - power ground and data, of the WS2812 type sometimes called Neopixels. Each LED has full independent colour control.
4) Four connection 5V - power ground data clock, sometimes called dot star. Each LED has full independent colour control.
https://learn.adafruit.com/adafruit-dotstar-leds/overview?view=all