Flickering Flame vs Sun Yellow

How close are they?

ΔE 6.5, close: similar, with a visible difference side by side. Sun Yellow is more saturated than Flickering Flame.

Can I use Sun Yellow instead of Flickering Flame?

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

Can I use Flickering Flame instead of Sun Yellow?

The same difference applies the other way round: Flickering Flame 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.