I want to stress from the very beginning that this chart is not perfect, that there are exceptions to every generality about every breed of dog, and that this chart is just one possible tool available to help determine a dog's breed. No tool replaces common sense.
All three of these breeds have "breed standards" which define the "ideal example of the breed". The problem is that most dogs are not ideal examples of their breed and by the time dogs get to rescue they may bear very little resemblance to any breed at all. Plus all three of these breeds have put the emphasis on working ability, intelligence, and temperment rather than a strict reading of the standards so there is a wide variety within each breed. Some dogs are turned in by owners who can identify the breed but, surprisingly (or maybe not so surprisingly), some owners mis-identify their dog's breed. All in all it can get very confusing
This chart was created by using the breed standards and the input of numerous people familiar with these breeds.
Because these breeds share so many similar traits and not any trait is singular to any one breed this chart allows multiple right answers to any question. On the left is a defining term, for example: "Tail? Yes " while the right side of the chart is three columns, one for each breed. If the dog has a tail you mark the blank box for BC and ES. There is a no in the Aussie column for this trait since most Aussies are either born tailess or have their tails docked soon after birth. Of course, some Aussies do have tails, and it's possible for the other breeds to not have tails. The goal with this chart is to try to chart most likely breed characteristics and find a trend for each dog. When you've answered all the questions possible, tally up the columns and chances are you can make a pretty educated guess about which breed of dog you are dealing with.
One final thought from the web page creator - rescue dogs are not breeding stock, their purity of lines or breed is fairly immaterial. If your dog looks and acts like a Border Collie, for example, then, for all it matters, it is a Border Collie. Be proud of your dog, love it for the great friend and companion it is, what breed it is or might be is minor compared to all the love your dog gives you.