Medium Rust vs T'au Light Ochre

How close are they?

ΔE 11.4, fair: the same colour family, but not a straight swap. T'au Light Ochre is a little darker, more muted than Medium Rust.

Can I use T'au Light Ochre instead of Medium Rust?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). T'au Light Ochre is a little darker, more muted than Medium Rust.

Can I use Medium Rust instead of T'au Light Ochre?

The same difference applies the other way round: Medium Rust is a little lighter, more saturated.

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.