Anthracite and bituminous are two types of coal that are formed differently and have different qualities. Anthracite is a hard, black coal that is often called "hard coal" and is formed from compressed layers of organic matter that have been exposed to great pressure. Bituminous coal, on the other hand, is a softer, black coal that is formed from the accumulation of organic matter in swampy areas. Some synonyms for anthracite include hard coal, black coal, and slate coal. Similarly, some synonyms for bituminous coal include soft coal, brown coal, and lignite. Both types of coal are used in various industries for energy production and other purposes.