A sheriff is elected by the county for a two-year, three-year or six-year term, according to the National Sheriffs' Association. Different states and counties have different terms and strategies for selecting the next sheriff.
Not all states have a sheriff, reports the National Sheriffs' Association. Connecticut has a state marshal system instead of a sheriff department. In Alaska, there are no county governments. Hawaii has deputy sheriffs who participate in the state’s sheriff’s division of the Hawaii Department of Public Safety, though they don’t have typical county sheriffs.
The main difference between a sheriff and a police chief is that a chief of police is a municipal employee who works for the city and is elected by the city’s mayor, notes the National Sheriffs' Association. A sheriff of a county is usually the highest elected law enforcement officer, who is elected by the county clerk, not the mayor. There is a sheriff’s office or a sheriff’s department depending on the county and state in question.
Different states also have different duties for sheriffs, according to Wikipedia. Some states have sheriffs who are sworn peace officers, while others are elected civilian officials who oversee the sworn peace officers. In some departments, there are different divisions such as a special deputy sheriff and a general deputy sheriff.