It becomes quite easy after looking at enough puppies and focusing on the right details. albeit “fluffier” than an adult coat, Fantoms coat is very typical of your standard stock coat puppy and in my opinion does not at all look remotely similar in coat type as the puppies the OP presented. Long coats just have a different look to them.... maybe hard to describe but not hard to spot. It’s more than fluffy... it’s like plush little wavy haired pudgy bear cubs with seemingly low ear sets.This is Fantom. He was quite fluffy as a pup but he turned out short- haired- it’s hard to tell.