ΔE 8.6, close: similar, with a visible difference side by side. Light Brown is a little darker, warmer than Tombstone Yellow.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Light Brown is a little darker, warmer than Tombstone Yellow.
The same difference applies the other way round: Tombstone Yellow is a little lighter, cooler.
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.
See Tombstone Yellow on the colour wheel See Light Brown on the colour wheel
All matches: Tombstone Yellow equivalents · Light Brown equivalents