Pastel Salmon vs Aggaros Dunes

How close are they?

ΔE 21.1, loose: different enough that you should pick on purpose. Aggaros Dunes is noticeably darker, more saturated, cooler than Pastel Salmon.

Can I use Aggaros Dunes instead of Pastel Salmon?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Aggaros Dunes is noticeably darker, more saturated, cooler than Pastel Salmon.

Can I use Pastel Salmon instead of Aggaros Dunes?

The same difference applies the other way round: Pastel Salmon is noticeably lighter, more muted, 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.