Pistachio vs Light Yellow

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Light Yellow is a little darker than Pistachio.

Can I use Light Yellow instead of Pistachio?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Light Yellow is a little darker than Pistachio.

Can I use Pistachio instead of Light Yellow?

The same difference applies the other way round: Pistachio is a little lighter.

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.