The precise figures vary in different countries, but commonly an extraordinary resolution must be affirmed by not less than 75% of members casting votes, whereas an ordinary resolution only requires a bare majority.
Some jurisdictions use both terms, while meaning slightly different things.
[1] The distinction was not maintained under the Companies Act 2006.
For example, in the United Kingdom, to liquidate a company voluntarily on the ground that it cannot by reason of its insolvency continue its business, requires an extraordinary resolution.
However, in certain circumstances a company may wish to amend its constitutional documents to provide that an extraordinary resolution needs to be passed prior to the company engaging in any reserved matters, purely as a matter of internal organisational control.