I found out that the relationship between yellow and orange is very complex.
L*c*h color space is known to be close to human perceptions. (L is lightness, c is chromaticity, and h is hue) According to L*c*h color space, yellow and orange have the same chromaticity and hue, but different lightness, which means orange color is a darker version of yellow.
However, I learned that orange color is the mixture of red and yellow, so they should be different kinds. In RGB color space, generally small values correspond to dark colors and large values light colors. (0,0,0) is complete black, and (255,255,255) is complete white. Here, yellow and orange have different portions of R, G, and B.
Which color space explains the relationship between yellow and orange better?