APT1608SURCK vs APT1608SURC

If you were to try and use these LEDs next to each other there would be a slightly noticeable difference in the color being the wavelength is different. Here is some info on wavelength Peak Wavelength vs. Dominant Wavelength in LED selection - Support / FAQs - Engineering and Component Solution Forum - TechForum │ Digi-Key (digikey.com).