Orange Magma vs Naples Yellow Deep

How close are they?

ΔE 17.1, loose: different enough that you should pick on purpose. Naples Yellow Deep is more saturated, cooler than Orange Magma.

Can I use Naples Yellow Deep instead of Orange Magma?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Naples Yellow Deep is more saturated, cooler than Orange Magma.

Can I use Orange Magma instead of Naples Yellow Deep?

The same difference applies the other way round: Orange Magma is more muted, 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.