There are several categories of users in SugarCRM. The very first is the Administrator which governs all the activities in the application. The Admin handles the issues like User Management, Role Management, System wide settings, Configurations settings and Email options. While creating the user admin can create user which he can assign the admin rights by selecting the Admin check box.
The next one is the Group user. Group users cannot login through the Sugar Suite web interface. These users are only used for assigning items to a group via Inbound Email functionality. All the email notifications will be send to these users when the projects are assigned. Same are the Portal users, they cannot login through the Sugar Suite web interface. These users are only used for portal web services. Normal users cannot be used for portal web services.

Apart from this you can set the user name and password,and many parameters like User Information, Address Information, you can also set the email options and inbound email settings for this user.