openerp - What it the Different from the HR Manager Users and HR Officer Users in Human Resource Concept in Odoo -

i have little bit confusion on user right security access , key roles , functionality access human resource concepts in odoo.

i have confusion around hr officer users , hr manager users whole human resource concepts in odoo.

i have found in case hr manager having full access not more administrator less access officer users in human resource management .

can 1 me how both users , key roles played in whole human resources in odoo ? ,

what reason behind add 2 users our human resource flow odoo ?

there normal difference between user access:

hr manager:will have access human resources configuration statistic reports.

hr officer: have able approve document created employees.

that's thing nothing else.