Last time I checked it was roughly double, but that didn't included the fact the house could have solar which isn't really an option for an apartment.

Impact is pretty much more heating/cooling required for house and I'd imagine that would compensate at least part of that.

So that’s the building itself, but then there’s the massive impact of a non-urban home due to network spread (roads, water, electricity, shops, services etc are all less carbon efficient when spread over large surfaces per capita)