Military Shader vs Coelia Greenshade

How close are they?

ΔE 26.9, loose: different enough that you should pick on purpose. Coelia Greenshade is noticeably lighter, cooler than Military Shader.

Can I use Coelia Greenshade instead of Military Shader?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Coelia Greenshade is noticeably lighter, cooler than Military Shader.

Can I use Military Shader instead of Coelia Greenshade?

The same difference applies the other way round: Military Shader is noticeably darker, warmer.

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.