Amarth Blue vs Light Sea Blue

How close are they?

ΔE 16.4, loose: different enough that you should pick on purpose. Light Sea Blue is noticeably lighter, more muted, cooler than Amarth Blue.

Can I use Light Sea Blue instead of Amarth Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Light Sea Blue is noticeably lighter, more muted, cooler than Amarth Blue.

Can I use Amarth Blue instead of Light Sea Blue?

The same difference applies the other way round: Amarth Blue is noticeably darker, more saturated, 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.