Well, we have 2 labrador retrievers here at home. And my dad did consider getting a Rottweiler before so I know a bit about them.

I don't think there's any major difference between the two, aside from the Rotts natural guarding abilities.
While both dogs are large breeds, Rotts do weigh a bit heavier and grow taller than the Labs. Both breeds are intelligent and reliable, though Rotts make better watchdogs because of their innate aggression and guarding abilities than Labs. But they do have to be trained while their still young, and should be handled carefully, especially around other dogs. Labs are suitable for children since they're loving and affectionate dogs, though they also make good watchdogs. They crave attention and care from what it considers as it's family. They're also easily trained and are good swimmers. Both breeds eat a lot, but Labs tend to get obese easily (probably since Rotts thrive on exercise

). No high maintenance for both breeds, just regular brushing.