Between a Furminator and a Coat King, do they work differently, which is best?

Yes they do work differently.  Choosing which is best depends on your dogs breed, coat type and what you are trying to achieve ;)    Coat Kings come in different sizes and are used in a different way to the furminator. 

I find the Furminator gets more coat out than the Coat King in a shorter time ;)  but it's easy to over do it too ;)

I think one of the main differences is that some of the coat kings can be used on matted coats whereas the furminator shouldn't be.

the furminator is a better shedding tool for smooth thick coats ie like labs
coat king is better on because of the wider teeth  double coats like lh gsds

i use both of mine to help with carding and handstripping on some dogs but not all the time
since ive had my furminator i hardly ever use my coat king
but be careful with the furminator because it can sratch the skin badly if u use it t hard

Would you say the Coat King is best for Golden Retriever then?

i use a coat king on my two labs, and it's not done any damage to their coat. It's a godsend to be honest - it gets loads of the loose hair out so there's less on the laminate!

if i had a goldie in for grooming i would not use the coat king i would use a slicker brush on the feathers and then go over with the furminator on the shorter tighter parts of the coat but i always use a slicker and a comb first to get most of the dead hair out

u should try a furminator on ur labs munkeemojo great for those types of coats

i might just :)