ΔE 6.9, close: similar, with a visible difference side by side. Clear Viridian is cooler than Greenskin. They are different kinds of paint: Army Painter Greenskin is an opaque base/layer paint and Reaper Clear Viridian is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Clear Viridian is cooler than Greenskin. They are different kinds of paint.
The same difference applies the other way round: Greenskin is 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 Greenskin on the colour wheel See Clear Viridian on the colour wheel
All matches: Greenskin equivalents · Clear Viridian equivalents