RAF Sky / FS 34424 vs Light Green Grey

How close are they?

ΔE 6.5, close: similar, with a visible difference side by side. Light Green Grey is a little darker, more muted than RAF Sky / FS 34424.

Can I use Light Green Grey instead of RAF Sky / FS 34424?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Light Green Grey is a little darker, more muted than RAF Sky / FS 34424.

Can I use RAF Sky / FS 34424 instead of Light Green Grey?

The same difference applies the other way round: RAF Sky / FS 34424 is a little lighter, 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.