Pyrrole Orange vs Hot Orange

How close are they?

ΔE 15.6, loose: different enough that you should pick on purpose. Hot Orange is a little darker, much more muted than Pyrrole Orange.

Can I use Hot Orange instead of Pyrrole Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Hot Orange is a little darker, much more muted than Pyrrole Orange.

Can I use Pyrrole Orange instead of Hot Orange?

The same difference applies the other way round: Pyrrole Orange is a little lighter, much 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.