Just a area of speculation as Freddy's full name is Freddy FAZBEAR and not Freddy the Bear, where as the other characters full names are Bonnie the bunny, Chica the chicken and Foxy the Pirate Fox. So does Freddy have a surname and is his surname Fazbear. Why do you think he is not referred to as Freddy the bear like all the other characters. I don't not it is just a curiosity of myself which I'm writing down for you to see.
Comment if your interested as well