In most organizations, both functional work and project work are taking place. There are some key differences between the two types of work.
Functional work is routine, on-going work. It is also sometimes called operations. Project work has a beginning and end, as well as a defined output.
Functional managers are responsible for their specific function or department such as accounting, manufacturing or marketing, and they provide technical direction. A project manager is responsible for a project and the results of the project, and helps to enable all project team members to perform their work.
People are usually “owned” by the functional organization. Resources from a functional organization are usually assigned to one or more projects, often on a part-time basis.
It can be challenging for a project manager if his team members also have functional responsibilities. The team members are often more motivated to please their functional managers than their project managers, since the functional managers are typically responsible for performance reviews and raises.

Materials are based on the Project Management Institute, A Guide to the Project Management Body of Knowledge, (PMBOK® Guide) 7th Edition, Project Management Institute, Inc., 2021
PMBOK is a registered mark of the Project Management Institute, Inc.