Thunder Storm vs Oxidation Green

How close are they?

ΔE 20.7, loose: different enough that you should pick on purpose. Oxidation Green is noticeably lighter, more muted, cooler than Thunder Storm.

Can I use Oxidation Green instead of Thunder Storm?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Oxidation Green is noticeably lighter, more muted, cooler than Thunder Storm.

Can I use Thunder Storm instead of Oxidation Green?

The same difference applies the other way round: Thunder Storm is noticeably darker, 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.