When a new team has just been formed in a workplace, it usually starts off with a team lead, with all the members working directly under the lead.
[L] / | \ [M] [M] [M] L = Team Lead M = Team Member
The lead maintains the backlog of tasks to be carried out by the members. Project and product management are mostly handled by the lead at this point, and given the freshness of the team, more rooms of innovation are usually allocated to the members. The member could work with the lead to start a new project, with the lead overseeing the progress and milestones for the project.
The methodology of work varies here, but usually having a agile ceremony seems to be an overkill at this stage. Kanban could work well.
As the number of project grows, and the lead also has a higher-up reporting to handle, project management tasks are best to be handled by a separate role instead.
[L] --- [PJM] / | \ [M] [M] [M] L = Team Lead M = Team Member PJM = Project Manager
The project manager works alongside with the lead, understanding the requirements of work and managing the timeline of different projects. The team members will still be working with the lead to clarify the requirements and details of the tasks. Along the progress of work, project manager would proactively ensure blockers are resolved, ensuring project’s on-time completion.
At the end of an agile sprint, or a quarter, the project manager sums up the progress of all on-going projects, and plans out the timeline for the overflowing tasks.
Slowly, with more projects and requirements that the lead received externally from the team, as well as internal projects started by the team members, the envisioning and future planning of these projects start to get out of hand. This calls for another role.
[L] / \ / \ [PJM]--o--[PDM] | / | \ [M] [M] [M] L = Team Lead M = Team Member PJM = Project Manager PDM = Product Manager o = Backlog
The backlog ownership is now offloaded from the lead. Instead, a product manager co-owns the backlog with the project manager. External requests received from the lead, or other members of the team will be propagated into the central backlog.
Internal projects that were started before having this structure, will also have its requirements centrally managed in the backlog, allowing the members to focus of the execution of project.
Meanwhile, product manager handles the envisioning and refinement of each project, making sure the project brings the most value to the necessary parties on its completion. For internal projects that were initially started by internal members, the product manager will work with the member, aligning their expectations on the project’s goal.
At the end of a sprint, or quarter, the project manager, as usual, wraps up the progress, and shares it with the lead and the product manager, all the while ensuring team members have sufficient resources to complete their tasks.