Nearly a tie: Greenland and United States differ by barely -77%% in area — about 2,154,754 km² km² against 9,439,424 km² km².
Both sit in North America, 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 0.2× you see above.
The old map muddied it further: Mercator inflates Greenland about 11.8× and United States about 2×, so on a Mercator-style map this pair appears 1.4× apart instead of the true 0.2×.
United States fits 0× into Greenland.