What's the difference between "cabinet" and "cupboard"?
A cupboard is a closed piece of furniture with one or more doors and possibly shelves. A cabinet is more like a closet, and might be built into a wall or a separate piece of furniture. Cabinets are typically considered general-purpose storage, while cupboards are more for food and dishes. The two are somewhat interchangeable, and you might say that a cupboard is a type of cabinet.
In British English, a cupboard can be what Americans would call a 'closet'. See: cupboards and closets.