ΔE 7.8, close: similar, with a visible difference side by side. Dark Elf Highlight is a little lighter than Dawnstone.
Can I use Dark Elf Highlight instead of Dawnstone?
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Dark Elf Highlight is a little lighter than Dawnstone.
Can I use Dawnstone instead of Dark Elf Highlight?
The same difference applies the other way round: Dawnstone is a little darker.
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.