ΔE 12.7, fair: the same colour family, but not a straight swap. Warp Lightning is noticeably lighter, cooler than Olive Green. They are different kinds of paint: AMMO by Mig Olive Green is an opaque base/layer paint and Citadel Warp Lightning is a one-coat contrast-style paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Warp Lightning is noticeably lighter, cooler than Olive Green. They are different kinds of paint.
The same difference applies the other way round: Olive Green is noticeably darker, 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 Olive Green on the colour wheel See Warp Lightning on the colour wheel
All matches: Olive Green equivalents · Warp Lightning equivalents