Bathrooms given as fractions is one of the oddities of US real estate that also is practical. 1 and 3/4 baths? You know one of them probably doesn't have a bathtub. 1 and 1/4 bath? Most likely the quarter one is just a toilet. Most bathrooms in Norway are 3/4 since most lack a bathtub.
Children outside without adult supervision. In the US, the 2010's brought on the idea of "free-range parenting" and suing for the right to do it. In Norway, children never stopped walking to school unaccompanied by adults, or stopped taking the bus by themselves, or stopped playing outside without grown-ups nearby.
Never going outside in my PJs. Americans will wear their sleeping garments outdoors, in public. They go shopping in their pajamas, fly on planes in their pajamas. I have never, ever seen a Norwegian do this, nor would I expect to since most Norwegians sleep in the nude.
Christmas lights. White in Norway, colored in the US. I like both but I also like that each country sticks to its tradition.
Number of rooms: In American, I live in a two-bedroom apartment. In Norwegian, I live in a three-room apartment.