Gobi Brown vs Light Green Chrom.

How close are they?

ΔE 15.2, loose: different enough that you should pick on purpose. Light Green Chrom. is more muted, cooler than Gobi Brown.

Can I use Light Green Chrom. instead of Gobi Brown?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Light Green Chrom. is more muted, cooler than Gobi Brown.

Can I use Gobi Brown instead of Light Green Chrom.?

The same difference applies the other way round: Gobi Brown is more saturated, 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.