The HL1606 is really limited in what it can do- each HL1606 can address several LEDs, but you can't really control what they do; basically running patterns are it.
These strips have a different control chip, and are also limited, but in different ways- you have complete control of each pixel, but each chip can only control a single pixel so the manufacturers save on chips by putting several RGB packages in a single pixel.
As for where we get them- we ordered them directly from a Chinese company.