IJA #31 Cha Kasshoku (Tea Colour) vs Rust

How close are they?

ΔE 6.7, close: similar, with a visible difference side by side. Rust is cooler than IJA #31 Cha Kasshoku (Tea Colour).

Can I use Rust instead of IJA #31 Cha Kasshoku (Tea Colour)?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Rust is cooler than IJA #31 Cha Kasshoku (Tea Colour).

Can I use IJA #31 Cha Kasshoku (Tea Colour) instead of Rust?

The same difference applies the other way round: IJA #31 Cha Kasshoku (Tea Colour) is 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.