ΔE 18.1, loose: different enough that you should pick on purpose. Beetle Green is noticeably darker, more saturated, cooler than Pearl Green. They are different kinds of paint: Tamiya Pearl Green is a pearl paint and Vallejo Beetle Green is a metallic, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Beetle Green is noticeably darker, more saturated, cooler than Pearl Green. They are different kinds of paint.
The same difference applies the other way round: Pearl Green is noticeably lighter, more muted, 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 Pearl Green on the colour wheel See Beetle Green on the colour wheel
All matches: Pearl Green equivalents · Beetle Green equivalents