The main difference between human resource management and personnel management is that one focuses on helping the employees and one focuses on helping the company. Personnel management is an older version of human resources management.
The entire reason personnel management was created in businesses was to help control things like administrative tasks regarding employees to increase the value of the workers to the company. Personnel management was created in a time period when the mind frame of employees was "live to work" ideals with the now older generations. So, personnel management focused on making employees more valuable to the company, with the company's long term objective at the forefront of the goals.
Human resource management began development when employees began being hired from a new generation, the "work to live" mind frame. Human resource management is designed to handle administrative tasks for the company, but with the employee's long term benefits as the most important goal, followed closely by the company's objectives. While personnel management put the company's welfare first, human resource management focuses on the employee's collective and individual welfare first in order to maximize their beneficial aspects to the company. Human resource management is more focused on developing employees to keep them happy at their job, because human resources realizes people are individuals and knows they will stay longer and be more productive if they are happy.