Meaty Ochre vs Yellow RLM04

How close are they?

ΔE 18.7, loose: different enough that you should pick on purpose. Yellow RLM04 is noticeably lighter, much more saturated than Meaty Ochre.

Can I use Yellow RLM04 instead of Meaty Ochre?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Yellow RLM04 is noticeably lighter, much more saturated than Meaty Ochre.

Can I use Meaty Ochre instead of Yellow RLM04?

The same difference applies the other way round: Meaty Ochre is noticeably darker, much 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.