The official name of this breed is "cane da pastore maremmano abruzzese" even if locally people tend to use other different and shorter names.
Maremma, because the first to introduce the breed into the Italian Kennel Club in 1898 decided to call it this way, taking the name from their area of residence and later edited the standard with this name. Abruzzese because it is rooted in traditions from the pastoral areas in the Abruzzo region, but also because it was defined a standard even under this name.
Therefore originally they were considered two distinct breeds, but 50 years ago it was decide to consolidate the breeds into one breed. Nowadays after more than 60 years and about thirty generations of dogs, it is not possibile to distinct the differences arising from the two names.
The double denomination is still today cause of endless discussions. This happens especially with groups of people who don't want to follow the criteria of the official dog standard, institutional and scientific, but dog lovers who are just giving their personal opinions derived from folklore and regional bond, also with regard to the characteristics of the dogs.
In my opinion the name is not so important, it is fondamental though to recognize uniquely those characters as typical of the breed, such as the coat, the size and the profiles of the head, sometimes not recognized by some people, that prefers different dogs.
These discussions unfortunately confusing in those people who have no specific knowledge of this breed.