Chipping vs Tree Ancient

How close are they?

ΔE 6.4, close: similar, with a visible difference side by side. Tree Ancient is a little darker, more muted, cooler than Chipping.

Can I use Tree Ancient instead of Chipping?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Tree Ancient is a little darker, more muted, cooler than Chipping.

Can I use Chipping instead of Tree Ancient?

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