Just what is the difference and/or advantage of either? Well, a purebred cat/dog means both of the parents were of the same breed. A pedigreed dog is purebred and has an ancestral history of at least five years recorded and logged with the Kennel Club.
This explanation comes from Yahoo Answers:
"A is a listing of on both the sire's and dam's side, going back some number of generations. A five generation pedigree is very common.
The function of a registry, such as that provided the AKC, is to keep these records, and certify to their accuracy. So if you have a puppy born to registered parents, when the puppy is registered, the registry will look in their records and provide a certified copy of its pedigree.
If all of those ancestors are of the same breed, you have a purebred dog. If they are of different breeds, then you have a mixed breed. AKC will not register , but an individual could keep a pedigree regardless of the different breeds that were involved. If a group is trying to establish a new breed, they would probably establish their own registry to keep track of pedigrees.
In summary, a pedigree is a listing of ancestors, a purebred is a pedigreed dog whose ancestors back some number of generations are all the same breed."
Here is some information on a pedigree cat:
"Pedigree cats are often considered special in some way – and can cost a large sum of money. However, it is better to think about pedigree cats as different, rather than ‘better’ than non-pedigrees (moggies). While moggies come from a real mix of cats, pedigrees are bred from specific and very similar others all from the same ‘breed’ or with other breeds either within a certain breed standard or to create a new breed. This means that a certain look or color can be selected for and even some behavior traits can be more likely to occur. However, it also means that the number of cats available to breed from is much reduced and hence the ‘gene pool’ is not large. So while the look of the cat you are seeking can be pretty much guaranteed, problems can arise because of the limited gene pool. If there are health problems or disorders within this pool, these can be passed on more readily to the next generation – this is what we call inherited disorders. You will find the most common ones referred to under the breeds if relevant.
The ‘look’ or ‘standard’ of some breeds may require what could be considered as extremes of body form – such as very short noses or lack of a tail, which may not be wonderful in terms of the cat’s health." http://www.icatcare.org/advice/cat-care/pedigree-cats-%E2%80%93-things-consider
Interesting stuff, and there is a lot of it to read out there. I will take a minute to brag on Tootsie Roll as she is a purebred pedigree with a AKC Championship Sire in her lineage....Now we all know why she is such a FAHSIONISTA!!