Teams definitely are forms of work groups, but not all work groups are teams. In fact, plain work groups are much more numerous than teams.
Work groups function on three levels:
  • Dependent level
  • Independent level
  • Interdependent level
Here's the breakdown.

Dependent-level work groups

Dependent-level work groups are the traditional work unit or department groups with a supervisor who plays a strong role as the boss. Almost everyone has had some experience with this work setup, especially in a first job.
Each person in a dependent-level work group has his or her own job and works under the close supervision of the boss. The boss is in charge and tells the employees the do's and don'ts in their jobs. Helping each other and covering for one another do not occur often and do so mostly under the direction of the supervisor. In fact, most problem solving, work assignments, and other decisions affecting the group come from the supervisor.
A dependent-level work group can perform well in the short term. But for the long run, because group members operate separately and mostly at the direction of the supervisor, such work groups don't seem to go anywhere. Maintaining the status quo and keeping operations under control are what they do best. Creating improvements, increasing productivity, and leveraging resources to support one another are quite uncommon with dependent-level work groups.

Independent-level work groups

Independent-level work groups are the most common form of work groups on the business scene. Like a dependent-level work group, each person is responsible for his or her own main area. But unlike the dependent level, the supervisor or manager tends not to function like the controlling boss. Instead, staff members work on their own assignments with general direction and minimal supervision.
Sales representatives, research scientists, accountants, lawyers, police officers, librarians, and teachers are among the professionals who tend to work in this fashion. People in those occupations come together in one department because they serve a common overall function, but almost everyone in the group works fairly independently.
If members of an independent-level work group receive the managerial guidance and support they need on the job, such a work group can perform quite well.

Interdependent-level work groups

Members of an interdependent-level work group rely on each other to get the work done. Sometimes members have their own roles and at other times they share responsibilities. Yet, in either case, they coordinate with one another to produce an overall product or set of outcomes. When this interdependence exists, you have a team. And by capitalizing on interdependence, the team demonstrates the truth of the old saying: The whole is greater than the sum of its parts.
An independent work group can often be brought up to speed faster than an interdependent group. It simply takes more time to get a group of individuals to work as a team than to set a group of individuals off on their independent assignments. Yet when teams move into a high-functioning and high-producing state, where they capitalize on interdependence, they can outperform all other types of work groups. So, if you want a quick fix, don't look to teams: but if you want to see strong results for the long term, do look to teams.
To call a group a team does not make them a team: wishing for them to work as a team doesn't work either. For a snapshot of the main differences between work groups and teams, take a look at Table 1. As you can see, work groups have a strong individual focus and teams have a strong collective focus. The individual is not lost on a team, but that person's work is coordinated to fit in with the greater good. Team concerns are much more focused on the outcomes of the overall unit rather than an individual's accomplishments.
Table 1: Difference Between Work Groups and Teams
Work Groups
Teams
Individual accountability
Individual and mutual accountability
Come together to share information and perspectives
Frequently come together for discussion, decision making, problem solving, and planning.
Focus on individual goals
Focus on team goals
Produce individual work products
Produce collective work products
Define individual roles, responsibilities, and tasks
Define individual roles, responsibilities, and tasks to help team do its work; often share and rotate them
Concern with one's own outcome and challenges
Concern with outcomes of everyone and challenges the team faces
Purpose, goals, approach to work shaped by manager
Purpose, goals, approach to work shaped by team leader with team members
Table 1 also indicates that teams meet more often than traditional work groups. Work groups may meet periodically, based on the manager's style, primarily to hear and share information. Teams, by comparison, do much more than communicate when they meet. Team meetings are forums for planning work, solving work problems, making decisions about work, and reviewing progress. In short, meetings are vital to a team's existence.
The last item in Table 1 is crucial: Team leadership is participatory, in contrast to the primarily manager-driven nature of regular work groups. On a team, the manager or team leader frequently involves team members in helping shape the goals and plans for getting the group's work done — may as well get them involved, they've got to do the work! But in other kinds of work groups, managers more commonly work with staff individually to set goals and determine assignments. Of course, in many cases, managers just assign work with little discussion or collaboration with the staff members. And staff are then left to figure out what's expected and how best to get it done.