Prior to the series' beginning, the Bukins could buy off a part of the building's attic for extra rooms, so apart from the lack of a cellar, the lack of a backdoor, a garage in a separate building instead of being adjacent to the house, and a balcony used instead of the yard, the layout of Bukins' flat looks like the Bundys' house.
The apartment is in a mess from some fixes in the house which were never finished, and in the show's early episodes an unfortunately placed construction site outside allowed people (and Baron, the family dog) to go in and out the Bukins' apartment by the balcony.
As a major change, instead of disappearing like Seven after a few episodes, Syoma stays with the Bukins until the end of the series, and the often bizarre explanations for his absence from events the whole family should attend became a running gag.
Also, the family dog Baron does not die and reincarnate, he remains the same until the end of the series.
The episode Requiem For The Dead Briard was however adapted, with Baron being sold to a rich person by Syoma instead of dying.