Princeton notes that the differences between CTO, CIO, CEO and COO revolve around sector-specific roles. CTO stands for Chief Technology Officer and is generally an executive position for technology companies. CIO stands for Chief Investment Officer or Chief Information Officer; the role depends on the industry. CEO stands for Chief Executive Officer and is the highest ranking officer, while COO stands for Chief Operations Officer.
According to Wikipedia, the CEO of an organization has the final decision over technical, human and financial operations within the organization. While other C-level positions are created to manage sector-specific roles, Princeton suggests these roles can vary depending on the sector. For instance, a CIO for one organization may oversee functions related to information technology, whereas a CIO for another organization may be responsible for investment management. This means one CIO is known as a Chief Information Officer, while the other is known as a Chief Investment Officer.
Princeton notes that all C-level positions report to the CEO. The COO, or Chief Operations Officer, of an organization is usually the president when there is a chairman or CEO and handles the day-to-day operations. Wikipedia explains that the relevant industry or sector creates the differences within C-level roles of an organization.