I think most breeds have different kinds of growl, well more or less, also not only different breeds but different individulas aswell, some does it more than others. Of the dogs I have now, Hera Galahad and Buffy does it, Zeus is more of a choked howl when he is "play talking" Galahad is a nut and does some "growling" every day accompanied by kicking in the air, swinging his head and going down on his chest so his butt is sticking up in the air. He is too funny to watch, id rather sit around and watch him do that, than go to a movie lol....
We had something else that most people though was a sign of being unfriendly here a few years ago. We fostered a border Collie, and he was real timid when he first got here, we had him for more than a year before he was ready to move out to a farm, anyway when he got comfortable with us and himself he showed that in the sweetest possible way. When we came home or when he was out in the yard and someone of us came out, he was smiling, and not just with the corners of the mouth. He was actually smiling BIG, pulled his lips over his teeth and opened his mouth, and looked just lik a person who is smiling with open mouth. Most people thought he was mad, but he was just sooooo happy to show how much he appreciated being loved. I have never seen that in a dog before or after, that was soooo cute
Marit