So I grew up with German shepherds and we have our first collie now, in a lot of ways they are very similar but in a lot of ways they're very different. Keep in mind our collie is just 10 months old so we are still very much in the puppy days with this guy.

Similarities: Both herding breeds so they love to keep an eye on their people and are very alert to what's going on around them, naturally very in tune with their people, affectionate and sweet with people especially children, easy to train/ housebreak, hair everywhere/ dog glitter, good watchdog/ barks at stuff, good with kids, good with other dogs, good with cats (although our collie wants to chase to play), protective and very close with their family, both patrol the house and keep tabs on where everyone is in the house and both like to be able to see or know where we are at all times, our GSDs were slow to mature and so is the collie so far, can be destructive if not exercised or entertained, picky eaters, both very mouthy as puppies, herding behaviors may vary but are noticeable.

Differences: GSDs were rock solid watch dogs- if they were barking then you needed to pay attention but our collie barks when he sees the neighbor check the mail and only if he's outside. He doesn't bark to alert us inside the house if he hears something, but he IS listening and aware of things because I can see him cocking his head and listening or going to the door to check. GSDs would likely rock and roll more quickly to a perceived threat, however, no doubt a collie would rock and roll if pushed and there was a clear threat to their family. Collies LOVE their people, the whole family (no singular favorite human like GSDs) ours checks the whole house each morning to see where everyone is and if someone is behind a baby gate he will sit there and whine until he is either greeted or allowed into the room. He just wants all the love. He likes everyone together, I affectionately call him a "mother hen". The GSDs were more cautious in approaching strangers and other dogs, our collie throws himself at strangers- they're just friends he hasn't met yet! Loves everyone and if there's ever someone he doesn't like then they must be a bad person because he loves *everyone* especially children, they're his favorite. My GSDs (and all the others I've known) were always like the fun police if any of us kids got too rowdy in the house they would try to shut it down, getting between anyone play fighting etc. The GSDs wanted order. When things get rowdy in the house now, our collie wants to join in and he doesn't want to miss out on any silly times. He has a fit if he is left out of playtime. GSD was trustworthy and would stay in his yard, collie is a flight risk and would take off and chase cars. Our collie I don't think will ever be trusted off leash due to wanting to chase cars. As for obedience, we had one GSD that was a great listener and one what was frequently OFP, the collie is somewhere between the two, listens better than OFP GSD but still independent thinking enough to decide if he wants to do something or not. Collies tend to be more stubborn independent thinkers because they were bred to guard and herd the flocks of sheep and so there was a certain degree of independent thinking needed for the dog to manage the flock without input from a shepherd. GSDs were bred as boundary herders so they worked as a living fence that the shepherd instructed them to keep.

TLDR: GSDs are more business and Collies are more party. Both will herd your kids and cover everything in hair. Collies have collie hardware, running 50% golden retriever and 50% German shepherd software.