ΔE 20.0, loose: different enough that you should pick on purpose. Amber Green is noticeably darker, more muted, warmer than Leviathan.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Amber Green is noticeably darker, more muted, warmer than Leviathan.
The same difference applies the other way round: Leviathan is noticeably 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 Leviathan on the colour wheel See Amber Green on the colour wheel
All matches: Leviathan equivalents · Amber Green equivalents