ΔE 18.6, loose: different enough that you should pick on purpose. Vermilion is noticeably darker, much more muted than The Red Baron.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Vermilion is noticeably darker, much more muted than The Red Baron.
The same difference applies the other way round: The Red Baron 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 The Red Baron on the colour wheel See Vermilion on the colour wheel
All matches: The Red Baron equivalents · Vermilion equivalents