China dwarfs Kazakhstan: about 9,371,225 km² km² against 2,712,747 km² km². At true size China is about 3.5× larger — the whole of Kazakhstan fits into China roughly 3 times.
Both sit in Asia, 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 3.5× you see above.
The old map muddied it further: Mercator inflates China about 1.6× and Kazakhstan about 2.3×, so on a Mercator-style map this pair appears 2.4× apart instead of the true 3.5×.
Kazakhstan fits 3× into China.