ΔE 10.5, fair: the same colour family, but not a straight swap. Space Grey is more muted, warmer than Leviathan Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Space Grey is more muted, warmer than Leviathan Blue.
The same difference applies the other way round: Leviathan Blue is more saturated, cooler.
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 Leviathan Blue on the colour wheel See Space Grey on the colour wheel
All matches: Leviathan Blue equivalents · Space Grey equivalents