ΔE 16.0, loose: different enough that you should pick on purpose. Abaddon Black is noticeably darker, much more muted than RAL 8017 Rotbraun.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Abaddon Black is noticeably darker, much more muted than RAL 8017 Rotbraun.
The same difference applies the other way round: RAL 8017 Rotbraun is noticeably 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 RAL 8017 Rotbraun on the colour wheel See Abaddon Black on the colour wheel
All matches: RAL 8017 Rotbraun equivalents · Abaddon Black equivalents