Lamb Breast is the traditional name in United States. Outside that tradition, butchers carry comparable lamb cuts under different names — sometimes the same anatomical piece, sometimes a close cousin. The alternatives below are grouped by country so you can match what your local butcher actually carries.
Both are cheap, collagen-rich lamb cuts that need long, slow cooking; interchangeable in stews and slow roasts.
Shoulder is the meatier substitute when a recipe calls for breast, with the same fat-to-collagen behaviour over a long cook.
Lamb breast is structurally the lamb equivalent of pork belly — alternating fat and lean layers that reward slow roasting or braising.