If we referring to the basic concept that Management skill is consist of the function of planning also (PDAC). I think HRP is a part of HRM. HRM is involving some functions and HRP is the function to ensure that the organization will always have enough manpower (usually in numbers but also can be in competencies) to run the organization or to achieve further targets of the organization.
12th April 2011 From Indonesia, Jakarta
HRM: Human resource is a process of planning, organizing, directing and controlling of the recourse’s and Functions of the organization...
1. HRD: Human resource development
2. HRP: Human resource planning
3. HRMIS: Human resource management Information System
4. Industrial law
5. Labour law
6. Compensation and wages
HRP: Human resource planning is a very vast subject, this function purely involved in Manpower recruitment for the organization.
From understanding the Manpower Need, Budget quotation, Number of employees need, Job description, Salary payable, technically skills, Experience or fresher, Education, Sourcing, screening, scheduling interview’s, Interviewing, Nego, Offering etc..
For more detail: you can get in Wikipedia
12th April 2011 From India, Bangalore