Shedding
Their coats shed differently: the Norwich 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 Norwich Terrier needs a brush once a week.
Temperament
They differ most on loyalty (Norwich Terrier: friendly with everyone; Yorkshire Terrier: sticks close to its people) and on independence (Norwich Terrier: cooperative, with its own ideas; Yorkshire Terrier: decides for itself).
Alike
They are much the same size as adults, about 5.5 kg (12 lb) for the Norwich Terrier and 5.1 kg (11 lb) for the Yorkshire Terrier.
Alike
Both are rated the same on affection: a lap or leaning dog.