The color on the left was produced by instructing the computer to activate 254 units of red phosphor and 94 units of green phosphor. This mixture of phosphors undoubtedly produces a color which appears orange.
The color on the right was produced by cutting the activation that produced the orange on the left in half. On the right the activation is 127 units of red and 47 units of green.
Does the color on the right appear brown to you? If it does, you now understand that brown is really dark orange.