The CAO role is a relatively new C-suite position, as is the chief data officer or CDO. Most organizations don't have both and when they don't, the titles tend to be used interchangeably. The general distinction is that the CAO focuses more on analytics and its business impact while the CDO is in charge of data management and data governance.
"The new roles are really designed to expand the use of data and expand the questions that data is used to answer," said Jennifer Belissent, principal analyst at Forrester. "It's changing the nature of data and analytics use in the organization, leveraging the new tools and techniques available, and creating a culture around the use of data in an organization."
Someone in your organization may already have some or all of a CAO's responsibilities and may be succeeding in the position without the title, which is fine. However, in some organizations a C-suite title and capability can help underscore the importance of the role and the organization's shift toward more strategic data usage.