When your organization has been producing models for well over 40 years, it's natural that you produce numerous different runs, series types and other variations. Such changes over the years can make it difficult for the novice collector.
Luckily, Breyer has stuck to four primary model sizes for most of the last four decades. There are a few special runs and series that do not conform to the standard sizes, and not all sizes have always been available, but let's just stick to the basics for now. For the most part, even special editions and select series conform to the basic scale guide provided below. For help identifying a specific model, there are a ton of resources, both online and off.
Traditional: the largest of all the Breyer model sizes. These models were meant to be played with and shown. For the most part, all models in this size category conform to a 1/9th scale of the original horse.
Classic: the second largest of the model sizes. Several different series fall under this size category, including the Pony Series. The majority of models in this size class are 1/12th scale. The Pony Series models are naturally smaller than other Classics, but so are real ponies.
Little Bit/Paddock Pals: typically 1/24th scale, these models were often part of sets that included barns and other accessories. However, not all models in this size class were sold in a set. This size class did not appear until the 1980s.
Stablemates: the smallest of the model sizes, these models are 1/32nd scale. Most often, these miniature Breyer horses are sold in play sets, including more than one horse, horse trailers, riders and other accessories.