밥(bap)
Cooked rice, the staple food and main component of a Korean meal
When to use
Staple food, Eating rice, Cooking rice, Rice bowl
The nuance
밥 is used strictly for the staple cooked rice itself or situations where rice is the main food; it cannot refer to soup or side dishes.
국(guk)
Soup or broth served alongside food, usually hot and liquid
When to use
Soup dish, Hot soup, Eating soup, Soup bowl
The nuance
국 refers to liquid soup or broth served with meals, distinct from solid rice or side dishes.
반찬(ban-chan, banchan)
Side dishes served with rice, usually various small dishes accompanying the main meal
When to use
Side dishes, Small plate dishes, Eating side dishes, Types of side dishes
The nuance
반찬 are various side dishes eaten with rice, distinct from soup (국) and staple rice (밥).