Size
The Schipperke comes in a wide range of sizes, 3–9 kg (6.6–20 lb) as an adult, against 6–11 kg (13–24 lb) for the Shetland Sheepdog.
Grooming
The Shetland Sheepdog needs more grooming, daily brushing, where the Schipperke needs a brush once a week.
Temperament
They differ most on independence (Schipperke: decides for itself; Shetland Sheepdog: keen to work with you) and on affection (Schipperke: affectionate on its own terms; Shetland Sheepdog: a lap or leaning dog).
Alike
Both are rated the same on loyalty: sticks close to its people.