I've been playing a seed from a youtuber. Playstyle, and realistic vs patchy climate, have made a big difference in whether I get the correct map or not. There are probably other settings that affect it too, but it sounds like we are both accepting defaults for most things.
Aside from that, there have been some builds that change the starting world. One of those occurred in the late 1.15 series. It wasn't a huge difference (for me), mostly a trader moving position and a change in the ruins (and lots more brush and tall grass).
Having said that, I believe there is also a way to copy your building to a new save, but I am not familiar with how that is done and have only seen someone mention it in discord.