The most common role for a project is the developer.
Access the project and its code reviews
Launch scans manually
Download any code review report
A project lead is responsible is used for users that have the authority to manage the project and its team. A project lead can:
Anything a developer can do, and
Configure the code criteria, selecting amongst the skills that are installed within the workspace.
Ignore an issue (this is useful, for example, when what appears to be a problem with your code comes from a conscious architectural decision)
Manage team members and their roles
Remove users from the team
Clayton lets you assign a role to your project team members. Read here if you want to know more.