what are different roll types?

There are three types of Roles

•  Portal Roles
• Organization Roles
•  Community Roles

These are also called Role scopes

 

 Roles are used to define permissions across their scope: across the portal, across an organization, or across a community. For example,consider a role which grants access to create a Message Board category. A Portal role would grant that access across the portal, wherever there was a Message Board portlet.
A Community role would grant that access only within a single community. An Organization
role would grant that access only within an Organization.

Because Roles are used strictly for portal security, they also do not have pages,like Communities and Organizations.Users, User Groups, Communities, or Organizations can be members of a role.