Deep Cyan vs Light Sea Blue

How close are they?

ΔE 7.1, close: similar, with a visible difference side by side. Light Sea Blue is more muted than Deep Cyan.

Can I use Light Sea Blue instead of Deep Cyan?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Light Sea Blue is more muted than Deep Cyan.

Can I use Deep Cyan instead of Light Sea Blue?

The same difference applies the other way round: Deep Cyan is more saturated.

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.