Role Centers in dyanmics axapta

A user profile is a set of default information for a specific role in an organization, such as Chief Financial Officer or Accounting Manager. The user profiles determine the content that is displayed on Role Center pages.
When a user is assigned to a profile, it specifies which Role Center the user sees when they open the Microsoft Dynamics AX 2009 client or an Enterprise Portal Web page.
Developers can create new role centers using the Homepage property.

Workflow
In Microsoft Dynamics AX 2009, the term workflow is defined in two ways:
Workflow is a System
Workflow is a system that is included in Microsoft Dynamics AX 2009. The
Workflow system provides functionality that can be used to create individual
workflows, or business processes.
Workflow is a Business Process
A workflow represents a business process that defines how a document “flows”through the system by showing who must process and approve it.