Colour vision deficiency and Monochromatic vision

Colour vision deficiency noun - Genetic inability to distinguish differences in hue.

Monochromatic vision and colour vision deficiency are semantically related. In some cases you can replace phrase "Monochromatic vision" with "Colour vision deficiency", this phrases are similar.

Monochromatic vision noun - Complete color blindness; colors can be differentiated only on the basis of brightness.

Colour vision deficiency and monochromatic vision are semantically related. You can use "Colour vision deficiency" instead a noun phrase "Monochromatic vision".