Choosing between a Labrador or a flat-coated retriever is difficult, because the two breeds share a great deal in common. Although the final choice might come down to what you plan to do with your dog, you're unlikely to go wrong with either breed.
The Lab and the flat-coated are similar in size, but there are differences between the two breeds besides the Lab's short, dense coat and the wavier, slightly longer hair of the flat-coated retriever. The Lab appears more compact than the longer-bodied flat-coated retriever. That extends to the head, as the Lab's muzzle is shorter than that of the flat-coated retriever. The latter's tail and legs are feathered, unlike the Lab.
While both the Lab and the flat-coated retriever appear in standard black, other shades are found only in the specific breed. That includes yellow and chocolate for Labs and liver for the flat-coated retriever. If you're looking for another shade, consider the flat-coated retriever's close cousin, the golden retriever.
If you think Labs are the ducks of the dog world, you haven't met a flat-coated retriever. He loves to get wet, whether it's a pond, backyard pool or the ocean. Depending on where you live and your lifestyle, that's a plus or a minus. Neither breed is a particularly good watchdog, but the flat-coated retriever is more likely to sound the alarm if a stranger arrives.
According to American Kennel Club dog registration statistics, the Labrador consistently ranks as the most popular dog in America. The flat-coated retrievers usually rank in somewhere in the 90s out of 175 breeds. That means it's probably easier for you to find a good breeder of Labs in your region than a breeder of the flat-coated retriever, simply as a result of supply and demand.
While both breeds are easy to train, the typical Lab is less likely to be distracted than the flat-coated retriever. That's one reason why Labs serve as dog of choice for guiding, therapy, search-and-rescue and other endeavors requiring absolute obedience. That doesn't meant the flat-coated retriever can't serve the same purposes, but it might take a little longer. He is generally a little goofier than his Lab playmate. That doesn't extend to field hunting, where this working dog excels and might exceed the average Lab's abilities.