ΔE 7.2, close: similar, with a visible difference side by side. Desert Tan is a little darker, warmer than Terran Khaki.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Desert Tan is a little darker, warmer than Terran Khaki.
The same difference applies the other way round: Terran Khaki is a little lighter, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Terran Khaki on the colour wheel See Desert Tan on the colour wheel
All matches: Terran Khaki equivalents · Desert Tan equivalents