A pet quality pup would be a yorkie that somehow doesn't quite meet the standard. Wrong color/type of coat, a bite not quite right, to large/small for breeding, anything like this. Some are closer to the standard than others. There are differences in pet quality, as far as looks go. Not as far as loving goes though.
The only reason papers are important to me (as a breeder) is places like CKC will take anyone's word that they have a purebred yorkie and paper it. Thus you may think your getting a Yorkie but maybe your really not. They only have to send in a picture and a couple signatures to get papers.
There is no reason for you as a pet owner to worry about the papers. You love your pets and that's all that matters, no matter what anyone else thinks.