I have had goldies for 40 years, and had a number of friends with labs.
They are both big strong dogs, the males especially, and need proper training so they don't "tigger" all over people (children) and knock them over.
Both breeds can suffer from hip and elbow trouble and you should look for ones where hips, elbows and eyes have been tested - you really really don't want the heartache and cost of a dog with those conditions. If the breeder can't show good results, walk away.
Both breeds are food motivated and can be very greedy. Good training is needed to prevent counter surfing and stealing. I have met some labs (and one of my goldens) who would literally eat until they were sick, then eat the sick.🤢
Have I mentioned chewing? 😂 All pups will chew, but for some the novelty never wears off. And if bored or unsupervised they WILL eat your best Italian sandles and your underwear.
Goldens in particular are water dogs - originally bred to retrieve birds from water - and the muddier the better. From observation labs are the same, but their coats don't pick up quite as much mud.
In both breeds the show lines tend to be bigger and blockier, and with goldens at least, can be a bit dim.
The working lines are slimmer and more active and cleverer - easier to train but need to be kept occupied as the devil finds work for idle paws (and jaws).
Goldens I think calm down sooner and are very people orientated. All mine have been good with children and matured into calm friendly family dogs.
It's the coat that is the main difference.
Both moult, labs have hair rather than fur- it's stiffer and sticks into fabrics.
Goldie fur- you never get rid of it. It's soft and fine like fluff and gets absolutely everywhere.
Pictures of my current retriever- age 10 weeks (gardening) and 7 (showing off)
Whichever you get, they are lovely