Shedding
Their coats shed differently: the Norfolk Terrier holds loose hair until it is brushed or clipped out, the Yorkshire Terrier sheds through the year.
Grooming
The Yorkshire Terrier needs more grooming, daily brushing, where the Norfolk Terrier needs a brush once a week.
Temperament
They differ most on affection (Norfolk Terrier: affectionate on its own terms; Yorkshire Terrier: a lap or leaning dog) and on independence (Norfolk Terrier: cooperative, with its own ideas; Yorkshire Terrier: decides for itself).
Alike
They are much the same size as adults, about 5.2 kg (11 lb) for the Norfolk Terrier and 5.1 kg (11 lb) for the Yorkshire Terrier.