The 219b seams to be a cooler light and the 219c seams to be the warmer one.
Congratulations on your Reylights.. Im a fan
I believe you are correct, and here is why
the 219b is probably the sw45k, it is 4500k color temperature, so indeed slightly cooler than the
4000k 219c
here is a visual showing 6 different 219c, including the 4000k (sm403), and one 219b 4500k, labeled sw45k...pic thanks to maukka:
and here are some of my lights, confirming the 4000k 219c sm403 is warmer than 4500k 219b sw45k:
other differences include that the 219c has a more yellow tint. Not as Pink a Tint as the sw45k
the third light in the photo is just there to help my phone show the relative differences in Tint. It is not only cooler color temperature, with more green tint than the others, it is also Low CRI.. I do not like to use that light at all.. because Im spoiled by Nichia High CRI options.
the sw45k is my favorite LED for daytime adapted edc
the 4000k would be more useful when Im adapted to incandescent light in the evening
both are good