Interestingly enough I have studied British construction/house design and here is what's different:

INSIDE:
* There are doors on every room.
* Walls are square.
* Hardwood floors are very rare.
* Curtains rather than blinds are used on windows.
* There is no standard 'large house' setup which you see in the US - no big enterance with the stairs, and the family/living room to the left or right: generally a British house is narrow and deep rather than wide.

OUTSIDE:
* The windows are pushed right up against the roof rather than leaving a space.
* Windows are very big and the frames are painted in strange colors.
* Front doors are painted in very bright colors.
* The roofs have stone tiles rather than fake tiles

CONSTRUCTION
* Bricks are used to hold the house up rather than decoration.
* British houses have a heating system called 'Radiation'. It is not as effective as central air, and doesn't permit air-conditioners to be but in at a later date.