Size
The Papillon comes in a wide range of sizes, 1.5–5 kg (3.3–11 lb) as an adult, against 3–4 kg (6.6–8.8 lb) for the Maltese.
Lifespan
In UK vet records the Papillon lives longer: a median of 14.5 years, against 13.1 for the Maltese.
Grooming
The Maltese needs more grooming, daily brushing, where the Papillon needs brushing a few times a week.
Temperament
They differ most on independence (Maltese: cooperative, with its own ideas; Papillon: keen to work with you) and on intelligence (Maltese: learns readily, likes games; Papillon: needs daily brain work).
Alike
Both are rated the same on affection: a lap or leaning dog.