ΔE 18.0, loose: different enough that you should pick on purpose. Bootstrap Leather is a little darker, warmer than Viper Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Bootstrap Leather is a little darker, warmer than Viper Brown.
The same difference applies the other way round: Viper Brown is a little lighter, cooler.
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 Viper Brown on the colour wheel See Bootstrap Leather on the colour wheel
All matches: Viper Brown equivalents · Bootstrap Leather equivalents