The thousands of K is just the colour temperature. 4300k is OEM slightly yellow, best light output, 6000k is more white and what most go for but with a little less light output. 8000k is what I have, slight blue tint in the white and what I think looks best, but slightly less light output again. The higher you go the less light is emitted. Personally I wouldn't go higher than 8000k but up to 20000k is available.
The colour chart goes yellow, white, blue, purple and finally green.