Black Cardamom and El Salvadorian Green Cardamom Pods are related, but they are not interchangeable in flavor. Green cardamom is usually floral, citrusy, sweet, and perfumed, which is why it works so well in chai, desserts, rice dishes, and bright spice blends.
Black cardamom is larger, darker, and much more savory. Its pods are traditionally dried over fire or in smoke-fired systems, so the flavor is smoky, earthy, resinous, piney, mentholated, and slightly camphorous. Use green cardamom when you want lift and perfume. Use black cardamom when you want smoke, woodsy depth, and slow-cooked savory complexity.
Buck's current cardamom shelf includes El Salvadorian Green Cardamom Pods, Black Cardamom, White Cardamom / Bai Dou Kou, and Ethiopian Cardamom (Korarima). Green is the classic sweet/floral pod for chai, rice, baking, and sweets. Black is smoky, resinous, and savory. White cardamom is gentler and camphor-cooling, useful in Chinese, Southeast Asian, brothy, and lighter savory cooking. Ethiopian cardamom, also called korarima, is warm, rounded, and Ethiopian/Eritrean in character, especially good in berbere-style blends, spiced butter, stews, coffee, and long-cooked savory dishes.