Hi,
I think Personnel management and HR management are almost the same..because both are related to the employees of the concern.Maybe the difference would lie where personnel management deals with management of each employee like their personal attitude, grievances, motivation etc...and HR management is personnel management along with everything else relating to the employee like salary, leaves, training and development of employees etc...
But it is in no way connected to Admin(arrange/manage for establishment). Admin management is a different thing all together , where the admin person is responsible for all the office related work like, maintain stationery, obtaining requirements; negotiating price, quality, and delivery; approving invoice etc.
Regards