ΔE 17.6, loose: different enough that you should pick on purpose. Emperor Gold is a little darker, much more muted than Rusty Brass.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Emperor Gold is a little darker, much more muted than Rusty Brass.
The same difference applies the other way round: Rusty Brass 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.
See Rusty Brass on the colour wheel See Emperor Gold on the colour wheel
All matches: Rusty Brass equivalents · Emperor Gold equivalents