ΔE 19.0, loose: different enough that you should pick on purpose. Rainforest is a little lighter, more saturated, cooler than Frog Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Rainforest is a little lighter, more saturated, cooler than Frog Green.
The same difference applies the other way round: Frog Green is a little darker, 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 Frog Green on the colour wheel See Rainforest on the colour wheel
All matches: Frog Green equivalents · Rainforest equivalents