Radiation Glow vs Orange

How close are they?

ΔE 15.5, loose: different enough that you should pick on purpose. Orange is a little darker, more saturated than Radiation Glow.

Can I use Orange instead of Radiation Glow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Orange is a little darker, more saturated than Radiation Glow.

Can I use Radiation Glow instead of Orange?

The same difference applies the other way round: Radiation Glow is a little lighter, more muted.

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.