IJN Gray Green Nakajima vs Light Blue RLM65

How close are they?

ΔE 7.6, close: similar, with a visible difference side by side. Light Blue RLM65 is more muted than IJN Gray Green Nakajima.

Can I use Light Blue RLM65 instead of IJN Gray Green Nakajima?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Light Blue RLM65 is more muted than IJN Gray Green Nakajima.

Can I use IJN Gray Green Nakajima instead of Light Blue RLM65?

The same difference applies the other way round: IJN Gray Green Nakajima is more saturated.

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.