Size
The Black and Tan Coonhound is larger on average: about 40 kg (88 lb) as an adult, against 30 kg (65 lb) for the American Foxhound.
Grooming
The American Foxhound needs more grooming, brushing a few times a week, where the Black and Tan Coonhound needs a brush once a week.
Temperament
They differ most on intelligence (American Foxhound: easy-going, simple routines; Black and Tan Coonhound: learns readily, likes games) and on handler demand (American Foxhound: needs an experienced owner; Black and Tan Coonhound: needs steady training).
Alike
Both are rated the same on independence: decides for itself.