To be honest they look the same to me, but one's more expensive than the other.
Both are in same level of management ,if there's a super manager .Management are include different positions such as director ,decision maker and executive .It can be one person for all position and if company it has large activity (employee) those positions are most higher positions of management department and executive position are include of section manager or for mans.(whom has direct contact with employee)
manager's chair looks newer than executive chair depends on who sit in chair more time