ΔE 22.2, loose: different enough that you should pick on purpose. Viridian Grim is noticeably darker, much more muted, cooler than Steel Helmet Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Viridian Grim is noticeably darker, much more muted, cooler than Steel Helmet Green.
The same difference applies the other way round: Steel Helmet Green is noticeably lighter, much more saturated, warmer.
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 Steel Helmet Green on the colour wheel See Viridian Grim on the colour wheel
All matches: Steel Helmet Green equivalents · Viridian Grim equivalents