IDF Gray 2 (-1981 Golan) vs US Sand

How close are they?

ΔE 8.0, close: similar, with a visible difference side by side. US Sand is more saturated than IDF Gray 2 (-1981 Golan).

Can I use US Sand instead of IDF Gray 2 (-1981 Golan)?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). US Sand is more saturated than IDF Gray 2 (-1981 Golan).

Can I use IDF Gray 2 (-1981 Golan) instead of US Sand?

The same difference applies the other way round: IDF Gray 2 (-1981 Golan) is more muted.

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.