Thunderhawk Blue vs Terror Blue-Grey

How close are they?

ΔE 7.1, close: similar, with a visible difference side by side. Terror Blue-Grey is more muted, warmer than Thunderhawk Blue.

Can I use Terror Blue-Grey instead of Thunderhawk Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Terror Blue-Grey is more muted, warmer than Thunderhawk Blue.

Can I use Thunderhawk Blue instead of Terror Blue-Grey?

The same difference applies the other way round: Thunderhawk Blue 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.