I believe this is how they work for instance on string of 100 bulbs (nodes)
Smart string bulbs are programmed individually with 3 channels (red, Green and Blue) which by using different intensity of each color you can chose the color of the bulb. Therefore you can have the string light up in sections or chase from on end to the other. For this example this would take up 300 channels.
Dumb strings can be programmed the different colors, but the whole string lights up with that color so you use 3 channels for the string.
Steve