ΔE 20.7, loose: different enough that you should pick on purpose. Lemon Yellow is noticeably lighter, more saturated than Frog Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Lemon Yellow is noticeably lighter, more saturated than Frog Green.
The same difference applies the other way round: Frog Green is noticeably darker, 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 Frog Green on the colour wheel See Lemon Yellow on the colour wheel
All matches: Frog Green equivalents · Lemon Yellow equivalents