Size
The Tibetan Terrier is much larger: about 11 kg (24 lb) as an adult, against 5.5 kg (12 lb) for the Tibetan Spaniel.
Lifespan
In UK vet records the Tibetan Spaniel lives longer: a median of 15.2 years, against 13.8 for the Tibetan Terrier.
Grooming
The Tibetan Terrier needs more grooming, daily brushing, where the Tibetan Spaniel needs brushing a few times a week.
Temperament
They differ most on independence (Tibetan Spaniel: decides for itself; Tibetan Terrier: cooperative, with its own ideas) and on handler demand (Tibetan Spaniel: suits a first-time owner; Tibetan Terrier: needs steady training).
Alike
Both are rated the same on loyalty: sticks close to its people.