I'm not sure if it's just decoration difference. But I think they can be setup together. But if you're serious, you should consider the Mini-Z track instead. I've tried this dnano track. As they are made of hard plastic, it's slippery and body paint can be easily scratched out when you hit the track side.
Contents of Set A and B are different. Anyway, forget about the home circuit track. You should try the new dnano carpet track in dnano HK. It's a lot bigger and fun to play with.