ΔE 20.7, loose: different enough that you should pick on purpose. Grey Blue RLM84 is noticeably darker, more saturated than N8 Neutral Gray.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Grey Blue RLM84 is noticeably darker, more saturated than N8 Neutral Gray.
The same difference applies the other way round: N8 Neutral Gray is noticeably lighter, 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 N8 Neutral Gray on the colour wheel See Grey Blue RLM84 on the colour wheel
All matches: N8 Neutral Gray equivalents · Grey Blue RLM84 equivalents