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