The term “accountant” is not a legally defined one. Therefore, while you have to be appropriately qualified to call yourself a “doctor”, anyone can call themselves an accountant.
In the UK and Ireland, there are six major professional accountancy bodies (who together, make up the Consultative Committee of Accountancy Bodies). Accountants who hold one of these six qualifications, sometimes they are referred to as a CCAB-qualified accountant (and job advertisements sometimes ask for a CCAB-qualified accountant, when they want a fully qualified accountant, but don’t mind which qualification the applicant holds).
Full membership of any of those six accountancy bodies, means that the person has passed a number of examinations and has completed several years of relevent practical experience. The practical experience will have had to satisfy a number of areas and levels of responsibility.
In the UK, if one was to think about a hierarchy of accounting qualifications, then CCAB accountants would be at the top.