Grooming
The Finnish Spitz needs more grooming, daily brushing, where the Norwegian Buhund needs a brush once a week.
Exercise
Plan for plenty of exercise with the Finnish Spitz, and a moderate amount with the Norwegian Buhund.
Temperament
They differ most on independence (Finnish Spitz: decides for itself; Norwegian Buhund: cooperative, with its own ideas) and on intelligence (Finnish Spitz: learns readily, likes games; Norwegian Buhund: needs daily brain work).
Alike
The Finnish Spitz and the Norwegian Buhund are much the same size as adults, both about 15 kg (33 lb).
Alike
Both are rated the same on voice: very vocal.