ΔE 15.4, loose: different enough that you should pick on purpose. Sand is a little darker, more muted, warmer than Thanatos Grey.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Sand is a little darker, more muted, warmer than Thanatos Grey.
The same difference applies the other way round: Thanatos Grey is a little lighter, 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 Thanatos Grey on the colour wheel See Sand on the colour wheel
All matches: Thanatos Grey equivalents · Sand equivalents