A team is commonly defined as a group of people working towards a common team goal. A group is defined as several individuals who may coordinate their efforts towards something, but are not necessarily working towards a specific goal. A team is technically a group, but a group is not necessarily a team.
A team is understood to be a group wherein thought goes into its formation. The team is often formulated based on its goals and formed around its goals. A good example of this is an accident investigation team. This is a team formed with a common goal, which is to investigate a crime. However, each member of the team is selected to investigate specific elements of the crime and then bring those elements together to find the cause of the accident.
In a non-business environment, a group is simply a group of people gathered to do something on an individual basis and they may or may not be together, such as fans watching a sporting event. On the other hand, a team is a group of people who are collectively working towards something, such as a sports team working to win a game by combining their talents.