ΔE 15.3, loose: different enough that you should pick on purpose. IDF Sand Grey is noticeably lighter, warmer than Bastion Grey.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). IDF Sand Grey is noticeably lighter, warmer than Bastion Grey.
The same difference applies the other way round: Bastion Grey is noticeably darker, 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 Bastion Grey on the colour wheel See IDF Sand Grey on the colour wheel
All matches: Bastion Grey equivalents · IDF Sand Grey equivalents