ΔE 30.7, loose: different enough that you should pick on purpose. Flubber Green is a little lighter, much more saturated than Mortarion Green Clear.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Flubber Green is a little lighter, much more saturated than Mortarion Green Clear.
The same difference applies the other way round: Mortarion Green Clear is a little darker, 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 Mortarion Green Clear on the colour wheel See Flubber Green on the colour wheel
All matches: Mortarion Green Clear equivalents · Flubber Green equivalents