Differences between the Lhasa Apso and Shih Tzu include facial structure, coat type and character. A Lhasa Apso's muzzle is a little lower on its face and longer than that of a Shih Tzu. The head of a Lhasa Apso is narrow, while a Shih Tzu's head is typically round and broad.
The bite of each dog is different as well; a Lhasa Apso's bite is only slightly undershot, while a Shih Tzu has a fully undershot bite. While both dogs are about the same in size and proportion, there are minor differences. A Lhasa Apso is normally around 10 or 11 inches tall and weighs from 12 to 18 pounds. A Shih Tzu is normally around 10.5 inches tall and weighs around 9 to 16 pounds. Both breeds have long, dense coats, but the Lhasa Apso's coat is straight and the Shih Tzu's coat may be slightly wavy. The origins of each breed have led them to have completely different personalities. According to The Nest, the Shih Tzu was originally introduced as a palace pet. As a result, it has a friendly demeanor and is naturally trusting of everyone it meets. However, the Lhasa Apso was primarily used as a watchdog and can be wary of unfamiliar people.