Closer than most people guess: Democratic Republic of the Congo (2,334,703 km² km²) is only about 25%% larger than Sudan (1,863,027 km² km²).
Both sit in Africa, so this is a same-region comparison: the new Equal Earth map draws both with the same honest geometry, and the real gap is exactly the 1.3× you see above.
The old Mercator map treated both about equally (1× vs 1.1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Sudan fits 1× into Democratic Republic of the Congo.