ΔE 13.2, fair: the same colour family, but not a straight swap. Brown Rose is noticeably lighter, more muted than Braunviolett RLM 81.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Brown Rose is noticeably lighter, more muted than Braunviolett RLM 81.
The same difference applies the other way round: Braunviolett RLM 81 is noticeably darker, 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 Braunviolett RLM 81 on the colour wheel See Brown Rose on the colour wheel
All matches: Braunviolett RLM 81 equivalents · Brown Rose equivalents