ΔE 17.2, loose: different enough that you should pick on purpose. Mars Orange is noticeably lighter, much more saturated than Skrag Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Mars Orange is noticeably lighter, much more saturated than Skrag Brown.
The same difference applies the other way round: Skrag Brown is noticeably darker, much more muted.
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 Skrag Brown on the colour wheel See Mars Orange on the colour wheel
All matches: Skrag Brown equivalents · Mars Orange equivalents