Heritage Breeds are those older breeds that were the main farm chicken flock breeds in the Countrys early days, either brought to North Americda by colonists or developed from breeds that were brought here. Many of these were displaced when the heavy production breeds used by the factory farms replaced the farm flocks for eggs or broilers. So increasingly the farm flocks fell by the wayside, a process increased as many people at the same time left farms for the cities especially after WW2.
Most Heritage Breeds are considered to be both egg producers and meat birds, albeit not laying as many eggs as the egg production breeds or producing broilers as fast as the heavy meat production breeds.
That said most Heritage CHicken Breeders feel that their homestead eggs have better flavor then the eggs bought in stores and that the meat from their birds has fuller and richer flavor then the production raised fryers. Freshness can be a part of this as the meat is often stored frozen and eggs are often weeks old before sold.
I and many others use the terms Heritage and Homestead interchangeably as for the most part they refer to the same breeds.
The name is also applied to other species of fowl grown in our early days, Ducks, Geese, Turkeys, Guineas and Pigeons also all have Heritage Breeds within them, many are considered critically endangered along with many of our Heritage Chicken Breeds.