Enterprise Env Factors and Organizational Process Assets

 Guys these two things are really very confusing. Cant distinguish them so clearly and couldnt formulate what kind of stuff falls in which category.

In Project Integration Mgmt chapter - Develop Project Mgmt plan- inputs (page 80)- "Project Mgmt Information system" is and Enterprise Env Factor. But I feel that it should be organizational process asset.

Can someone explain me the difference.