Pastel Yellow vs Ice Yellow

How close are they?

ΔE 6.7, close: similar, with a visible difference side by side. Ice Yellow is more muted, warmer than Pastel Yellow.

Can I use Ice Yellow instead of Pastel Yellow?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Ice Yellow is more muted, warmer than Pastel Yellow.

Can I use Pastel Yellow instead of Ice Yellow?

The same difference applies the other way round: Pastel Yellow is more saturated, 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.