In QAComplete, a project as a workspace that divides your data for security purposes. Your team will determine if it is best to use one single project, or if separating the data into multiple projects makes sense.
The simplest way to store your data is in a single project. You can use filters to return information within the project based on specific criteria. A single project also reduces maintenance, as you can setup your choice lists, custom fields, and screen layouts once without worrying about synchronizing those in multiple projects.
Your teams can be assigned to different security groups within the project.
If you have different departments or teams within your organization that will work with the features in a different ways, such as different custom fields, workflow, screen layouts and choice list values, you may want to define more than one project.
You may also prefer to use multiple projects to secure the data so that some teams can access certain projects and features but not others. For example, if you have multiple departments and you do not want one department to see information from another department, you can achieve this by using multiple projects and setting security to prevent unauthorized project access, or you may have a team that needs read-only access to one project but update and delete in another.
Finally, you may want to separate your data into multiple projects for business reasons (for example, by product lines).