Shedding
Their coats shed differently: the Field Spaniel sheds through the year, the Sussex Spaniel moults most as the seasons change.
Grooming
The Field Spaniel needs more grooming, daily brushing, where the Sussex Spaniel needs brushing a few times a week.
Temperament
They differ most on voice (Field Spaniel: quiet; Sussex Spaniel: very vocal) and on intelligence (Field Spaniel: learns readily, likes games; Sussex Spaniel: easy-going, simple routines).
Alike
They are much the same size as adults, about 22 kg (47 lb) for the Field Spaniel and 19 kg (43 lb) for the Sussex Spaniel.
Alike
Both are rated the same on affection: a lap or leaning dog.