What makes a team rather than a group

A group of people reporting to the same manager is not a team. A team is a group where people depend on each other, cover for each other, and share responsibility for an outcome.

The difference shows in one behaviour: whether somebody who finishes their work helps with somebody else's, or waits. In a group they wait, because their work is done and the rest is not their problem. That is not a character flaw; it is what the structure taught them.

What produces a real team. A shared goal that requires everybody. Interdependent work rather than parallel work. Enough contact to know each other. And a leader who rewards the collective outcome rather than only individual output.

The single largest factor, and this is one of the more robustly supported findings in the research on teams, is psychological safety: whether people believe they can admit a mistake, ask a stupid question, disagree with the manager, or say they are stuck, without it being held against them. Teams with it outperform teams with more talented individuals and without it.

How you can tell whether you have it. Does anybody tell you bad news early? Does anybody disagree with you in a meeting? Does anybody say "I do not understand"? If the honest answer to all three is no, you do not have it, whatever anybody says when asked.

And it is built by the leader's reaction to the first person who takes the risk. Everybody watches what happens to them.