I think of collies more as a family of dogs many of which don't necessarily carry the name collie.
You have your AKC Collie...derived from the Scotch Collie in England. The 'Collie' was at one time called the 'Scotch Collie' but even then it was a shadow of the real small time english farmer's collie. Rough and Smooth are now two separate breeds.
I mentioned how the old farmer's 'Scotch Collie' is now gone? Well it's been extinct in the UK for 150+ years. But many of the early immigrants from Great Britain brought their dogs here, including the Scotch Collie. Here in the USA, these dogs were bred based on ability, and were mixed with local mutts, and with various herding dogs brought in by other immigrants.
This more honest farmer's dog lived on as a generic 'collie' until roughly world war 2, although the dogs in general were becoming less common since about World War 1, as small farmers moved off their lands and into factory jobs in cities.
From this pool of 'American Collies' (strongly influenced by their Great British roots, but blended with other things like the people of this nation) people developed three distinct officially recognized breeds.
You have the
Australian Shepherd (nothing Australian about it) which was a subset of American Collies who best met the needs of the more western style of farms. While all these 'American Collies' can do everything, the Aussie is a little bit more geared toward cattle and horses. Physically it is more square, sometimes born without a tail, and frequently is seen with the merle color. This dog was relatively recently recognized by the AKC. Note, however, MOST aussie owners were against AKC recognition because they felt it would turn the dog into more of a show dog and less of a farm dog.
You have the
English Shepherd. This is really the Eastern type of the American Collie, who best met the needs of those midwestern farmers. These dogs can herd anything, but wasn't really specialized in handling a big herd of a single type, they were more about helping the farmer who had 5 milk cows, 10 sheep, some pigs, some geese, etc. These dogs are very much of the mindset of 'everything has a place, and they should be IN IT! It fits, as the farms were it developed needed the pigs to stay in the pig pen, the sheep to stay in one area of the pasture, the milk cows to come in for milking, etc. He was also about protecting the farm from rats, and alerting a farmer when a neighboring human stopped by. Much before the Aussie Shepherd joined the AKC, a group of people tried to get the English Collie to be recognized as a breed. However the collie people objected to another dog with the name Collie (they also stopped the Shetland Collie from having that name, which is why we have the Shetland Sheepdog as a breed). This Eastern Strain of collie came in coats of tan-and-white (shared with the AKC collie) Tan-Black-and-White (also shared with the AKC collie) Black-and-White, and Black and Tan. The Collie people said that even after the name change, the English Shepherd was too similar in color. So for a while the English Shepherd people favored the black-and-tan color. This still didn't satisfy the AKC collie folks, so at long last the English Shepherd people said 'Fuck You Kennel Club' and went their own way.
You have the
Old Time Farm Shepherd, sometimes called the
Old Time Scotch Collie. This is the Midwestern version of the American Collie. In some ways it is like the English Shepherd in that it sprang from the need of small frontier farmers in roughly the time of the civil war, when each farmer had just a few of each type of livestock, and a fair amount of cropland. OTFS took a different approach. Rather than always rushing around making sure everything was in the right spot, they found a sunny spot to sleep, popping an eye open to to check on things. They were viewed as being extremely smart, figuring out what the farmer wanted done before the command was even issued. A bigger part of their roll than most of the other American Collies was their roll as both protector and hunter. The OTFC was expected to go squirrel hunting, or really hunting any game mammal with his farmer. He was expected to sniff out a trail, run it to it's den or up a tree, and to circle the tree so the farmer could get off a shot. The OTFS was expected to be an excellent ratter, and to fight off the racoons who would come in to much corn at night. (The OTFS can often seem to be more active at night vs during the day...maybe that's why all the naps) but to also watch out for human intruders. The OTFS isn't aggressive toward strange humans, but they are stand-offish and view everyone with a bit of suspicion. Unfortunately, people only started championing the OTFS in the late 1980s By that time there were hardly any of the dogs left. It is on the brink of extinction, and it's rarity is compounded by the number of people who will take an AKC collie and cross it with any other collie listed above, or a mutt in general, and call the result an 'old time farm shepherd'
And finally, you have the
Border Collie. At one time in Great Britain you had many different types of collies, all a bit different, all specializing in what the farmers of that region needed. The Border Collie was a dog that specialized in medium flocks of sheep who were left to their own devices for the most part on rocky terrain. The farmer would not interact with the sheep a lot, but would need them rounded up and brought in a few times a year The sheep would be a bit wary of humans due to low exposure, would be on rough terrain, and would be in small packs. The Border Collie excelled i working off of vocal commands or no commands and gathering up a handful of sheep and moving them to a designated area, then going after another handful. Repeat as necessary, building up the flock as you go, and making sure it stayed together and moved where desired.
(Compare to the herders who brought their flocks in every night, or herders whose dogs helped them move big flocks to market, or herders who lived with their herds in the pastures and mountains whose dogs kept the herd together. Note some will say BCs are the best herders of all. They are not. They are really really good at that style, and that style has been found to work great for many different farmers, but just one example, they couldn't handle the size of flocks the New Zealanders used so the NZers developed their own specialty dogs mixing BC, other collie types, and local dogs ).
Note I do NOT include the Border Collie in with the American Collie. They are cousins. the Border Collie lasted in strong numbers for many years after most of the other regional collies in the UK went extinct. There has been constant influx of UK Border Collies imported to the USA keeping the US and UK dogs very similar and genetically linked. While some of these UK imports contributed to the three American Collie breeds, for the most part the American Collies got a big important infusion of UK Collie once, and then developed on their own with only local dog or non English Herding dogs contributing to their gene pool.
ANYWAYS sorry for the long history lesson BUT...
What I am trying to get to in my ramblings is, if you want a collie, don't limit yourself to the "Collie" and instead expand you search to include the Aussie, the English Shepherd, and the OTFS (if you happen to be able to find any), the dogs who carry on the true heart of the Collie even if they don't carry the name.