Natasha is a much more confident and self-assured dog than Callie the border collie ever was. She learned a lot from Callie about how to fit into this household, but has applied the lessons in her own special way. Callie died suddenly about three weeks ago, after 10 years with us.
The biggest difference so far is the dog's relationship with Bertie the black cat (age 11). Actually, I'm not sure how much of the difference is a function of Bertie's attitude or the dog's. Natasha seems to treat Bert the same way Callie did, nipping at him and teasing him, but Callie was a much bigger animal and the cat might just have been afraid of her. He's not afraid of Natasha.
For us it means living differently. We no longer have to separate the two animals by closing doors and arranging schedules so that one animal or the other can be in the house. Bertie and Natasha co-exist, more or less peacefully, though the cat often seems to "run screaming from the room" when the puppy gets too rambunctious.