Natural Langue Control allows you to choose and fade in different color spaces:
From CONTROL | COLOR | WHEELS yellow wheel allows you to choose which space you want to work in. For the lights that use this space, any cues recorded then played back will fade in this color space too. This can give dramatically different looks when running the show. Fading in RGB or CMY (similar to how consoles without Natural Language Control would fade DMX) you can sometimes see a muddy or peaky tone mid fade. Fading in HSV (Subtle) fades saturation linearly, but ensures the hue avoids color shifts that look unnatural when going from cue to cue.
Choosing colors in HSV (Subtle) and HSV (Rainbow) is identical, but if you record and play a cue or memory using HSV (Rainbow) you will see dramatic color shifts during execution. Hue is defined in degrees where 0° is red as is 360°. Cyan is at 180°.
Regardless of the color space you choose, on many lights there is also a wheel bank that deals with Color Correction. That allows you to choose the white point and also deals with the Amber and White components of RGBW, RGBA and RGBAW lights.
See NLC - Color Spaces for further explanation and graphical examples.