My Artie is fearless towards any Dog Breed and any person, he goes right up and greets everyone and everything from Dogs to Mules, skunks and racoons, pigs, goats you name it! But he's afraid of the vaccuum cleaner.

I don't understand it?
But Abigail is only 9 weeks old now and she doesn't care for other dogs, except Artie and only some people can pet her she is leery of everyone?
So I guess it's just their different personalities?