ΔE 6.3, close: similar, with a visible difference side by side. Grey Blue RLM84 is more saturated than RAF Camouflage (Barley) Grey BS381C/626.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Grey Blue RLM84 is more saturated than RAF Camouflage (Barley) Grey BS381C/626.
The same difference applies the other way round: RAF Camouflage (Barley) Grey BS381C/626 is more muted.
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.
See RAF Camouflage (Barley) Grey BS381C/626 on the colour wheel See Grey Blue RLM84 on the colour wheel
All matches: RAF Camouflage (Barley) Grey BS381C/626 equivalents · Grey Blue RLM84 equivalents