Strong Dark Blue vs Thunder Storm

How close are they?

ΔE 7.0, close: similar, with a visible difference side by side. Thunder Storm is a little lighter, cooler than Strong Dark Blue.

Can I use Thunder Storm instead of Strong Dark Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Thunder Storm is a little lighter, cooler than Strong Dark Blue.

Can I use Strong Dark Blue instead of Thunder Storm?

The same difference applies the other way round: Strong Dark Blue is a little darker, warmer.

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.