ΔE 20.7, loose: different enough that you should pick on purpose. Mahogany is noticeably darker, much more muted, cooler than Cygor Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Mahogany is noticeably darker, much more muted, cooler than Cygor Brown.
The same difference applies the other way round: Cygor Brown is noticeably lighter, much more saturated, 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.
See Cygor Brown on the colour wheel See Mahogany on the colour wheel
All matches: Cygor Brown equivalents · Mahogany equivalents