Orange Tan vs Tan Yellow

How close are they?

ΔE 6.9, close: similar, with a visible difference side by side. Tan Yellow is a little lighter than Orange Tan.

Can I use Tan Yellow instead of Orange Tan?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Tan Yellow is a little lighter than Orange Tan.

Can I use Orange Tan instead of Tan Yellow?

The same difference applies the other way round: Orange Tan is a little darker.

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.