Boards can be either decision makers or problem solvers. These are the two main board structures:
Governance Boards oversee the management of the business, define the strategy and the risk appetite for the management. This type of board will make decisions that affect the direction that the organisation will travel.
Advisory Boards are problem solvers that provide input to Governance Board decision making. This type of board could be project or function based.
They are more powerful that Board sub-committees because they can involve internal or external people and utilise a wider range of skills and experience.