There is only one account name.
The account name is visible in emails if using formatted The account name is a part of the email sent and visible to end-users.
Finally, the account name is visible on login page/prompt and is only editable by system administrators.
If using one instance, reporting is centralized but customized to share reports with specific users, groups, companies. A report will restrict access to some data based on folder access, but not the following reports if the user is set up for global report viewing.
Reporting filter selections and column selections are the same for all users.
Quick Selections for column views set for global availability will be for everybody. The default global selection setting is available as one setting for all users. There is no separate default by organization.
All Administration fields are globally configured. Users, Groups, Companies, Project Settings, etc. are available to all users and cannot be restricted by different organizations in the same instance.