The CEO (Chief Executive Officer) is the leader of a company and is responsible for directing and setting the organization’s policies, vision, and goals. CEOs have authority over all other company personnel as they have the last say in policy and management decision-making. The CEO also answers to the board of directors.
COO stands for Chief Operating Officer and is a position only found in larger companies. The COO (Chief Operations Officer) reports to and is the right-hand man to the CEO and oversees the functions and general operations of a company. These responsibilities are typically the responsibility of the CEO, however, when a company becomes too large, a COO is needed to lessen the burden.
The COO will often be involved in advising and helping the CEO with decision-making, establishing a vision for the company's future, and determining how to lead going forward. With the support of the CEO and the board of directors, the COO will lead the execution of a company's strategy, and will ultimately be responsible for its performance.
The COO also works closely with the Chief Financial Officer (CFO), Chief Information Officer (CIO), and other officers to make appropriate operational adjustments. Ultimately, the COO reports to the CEO and advises him/her on issues regarding the structure of the company and operations.
In summary:
A CEO:
Comes up with the creative vision
Pitches the company
Raises funding
Makes executive decisions
Holds meetings with COO, CTO, etc.
Hires and fires people
Answers to the board of directors
Keeps all departments in check
A COO:
Executes the CEO's vision
Manages daily operations
Makes operational decisions
Helps prepare documentation
Helps manage employees
Helps manage the various teams
Guides other executives with important tasks
Helps the CEO gather important information
