ΔE 6.7, close: similar, with a visible difference side by side. Olive Drab is a little darker, warmer than WWI German Light Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Olive Drab is a little darker, warmer than WWI German Light Green.
The same difference applies the other way round: WWI German Light Green is a little lighter, 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 WWI German Light Green on the colour wheel See Olive Drab on the colour wheel
All matches: WWI German Light Green equivalents · Olive Drab equivalents