ΔE 12.2, fair: the same colour family, but not a straight swap. Lemon Yellow is a little darker, more muted than Cadmium Yellow Medium Hue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Lemon Yellow is a little darker, more muted than Cadmium Yellow Medium Hue.
The same difference applies the other way round: Cadmium Yellow Medium Hue is a little lighter, 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 Cadmium Yellow Medium Hue on the colour wheel See Lemon Yellow on the colour wheel
All matches: Cadmium Yellow Medium Hue equivalents · Lemon Yellow equivalents