ΔE 8.8, close: similar, with a visible difference side by side. Grey Violet RLM75 is a little darker than Dawnstone.
Can I use Grey Violet RLM75 instead of Dawnstone?
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Grey Violet RLM75 is a little darker than Dawnstone.
Can I use Dawnstone instead of Grey Violet RLM75?
The same difference applies the other way round: Dawnstone is a little lighter.
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.