This document outlines the key differences between a project manager and a functional manager. A project manager is needed to oversee time-bound projects with limited budgets and resources, such as constructing a new building, designing new software, or conducting clinical drug tests. To successfully manage such projects, a project manager must define goals and estimates, manage budgets and deadlines, build and lead a team, develop communication and risk management plans, and integrate all relevant plans into a single executable project plan. In contrast, functional managers lack expertise in these project management knowledge areas required to oversee time-bound projects with strict constraints.