Kazakhstan is clearly the larger of the two: about 2,712,747 km² km² against 1,925,871 km² km², roughly 1.4× at true size. Drag one onto the other on the map above to feel the gap.
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 1.4× you see above.
The old map muddied it further: Mercator inflates Kazakhstan about 2.3× and Saudi Arabia about 1.2×, so on a Mercator-style map this pair appears 2.7× apart instead of the true 1.4×.
Saudi Arabia fits 1× into Kazakhstan.