The settings for session duration and password policies at the profile level override the settings at the organization level.

 

Until you set the Session Timeout on a profile, the organization-wide Timeout value in the Session Settings applies to users of the profile. Once set, the Session Timeout on a profile overrides the organization-wide Timeout value for users of that profile. Changes to the organization-wide Timeout value will not apply to users of a profile with its own Session Timeout value.

http://docs.releasenotes.salesforce.com/en-us/winter15/release-notes/rn_forcecom_security_profile_additions.htm

Profile specific:

The settings for session duration and password policies at the profile level override the settings at the organization level.

Until you set the Session Timeout on a profile, the organization-wide Timeout value in the Session Settings applies to users of the profile. Once set, the Session Timeout on a profile overrides the organization-wide Timeout value for users of that profile. Changes to the organization-wide Timeout value will not apply to users of a profile with its own Session Timeout value.

http://docs.releasenotes.salesforce.com/en-us/winter15/release-notes/rn_forcecom_security_profile_additions.htm

Org wide:

Profile specific: