ΔE 8.5, close: similar, with a visible difference side by side. Medium Yellow is a little lighter than Yellow FS13538.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Medium Yellow is a little lighter than Yellow FS13538.
The same difference applies the other way round: Yellow FS13538 is a little darker.
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 Yellow FS13538 on the colour wheel See Medium Yellow on the colour wheel
All matches: Yellow FS13538 equivalents · Medium Yellow equivalents