The words 'team' and 'group' are often used interchangeably.
"A team is a small number of people with complementary skills who are committed to a common purpose, performance goals, and approach for which they are mutually accountable" (Kazenbatch & Smith, 1994).
Teamwork involves members working interdependently upon a task, whereas members of a group can work independently of each other towards the completion of a task.
Team members will have the same objective when working on a project.
In contrast, the required project outcome may not be the first priority for members of a group. A simple example here is when someone with a particular expertise is invited to join a group needing their knowledge. The outcome of the project is not necessarily important to this expert, but being able to say that they have been invited to join the group will add credence to their resume.