ΔE 19.8, loose: different enough that you should pick on purpose. IJA Grey Green is noticeably darker, much more muted than 'Jack Bone.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). IJA Grey Green is noticeably darker, much more muted than 'Jack Bone.
The same difference applies the other way round: 'Jack Bone is noticeably lighter, much more saturated.
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 'Jack Bone on the colour wheel See IJA Grey Green on the colour wheel
All matches: 'Jack Bone equivalents · IJA Grey Green equivalents