I don’t think there’s any definitive answer https://cotedetexas.blogspot.com/2018/06/harry-meghans-new-house-pssst-i-found.html the 9th photo in this article has a nice birds eye view of the two apartments.
This article https://www.businessinsider.com/pri...her-royals-all-live-in-the-same-palace-2018-5 claims that apt. 1 is slightly larger than apt. 1A.
Really apt. 1 is slightly bigger when everyone has said 1A is the largest?