Trollslayer Orange vs Orange Yellow

How close are they?

ΔE 7.1, close: similar, with a visible difference side by side. Orange Yellow is more saturated than Trollslayer Orange.

Can I use Orange Yellow instead of Trollslayer Orange?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Orange Yellow is more saturated than Trollslayer Orange.

Can I use Trollslayer Orange instead of Orange Yellow?

The same difference applies the other way round: Trollslayer Orange is 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.