Indian Yellow Hue vs Yellow RLM04

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Yellow RLM04 is a little darker, cooler than Indian Yellow Hue.

Can I use Yellow RLM04 instead of Indian Yellow Hue?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Yellow RLM04 is a little darker, cooler than Indian Yellow Hue.

Can I use Indian Yellow Hue instead of Yellow RLM04?

The same difference applies the other way round: Indian Yellow Hue is a little lighter, 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.