I have found that with most "dog terms" they vary as much as the people that use the terms. I have come to realize that a lot of dog terms you really have to take into consideration the person that you are talking to (or online, the person whose is using the term).
I am sure that there are people that will explain it further than that MUCH better than I could.
I am sure that there are people that will explain it further than that MUCH better than I could.