The Committee are responsible for the running of the society.
The roles indicated here are a guidline to the sorts of things that each memeber of the committee should be doing. However, it is not set in stone. For example
- The publicity officer may send the weekly emails instead of the secretary
- The treasurer may book venues instead of the president
- The band leader may book rooms instead of the secretary
And so on.
As long as all of the tasks are completed where they are required, and the society runs smoothly, it doesn't actually matter who does what job. However, it is important that things are distributed fairly. No one person should end up doing any more than any other. It is the job of the president to coordinate the roles, and the role of the committee to decide at the committee meetings who is responsible for completing which tasks.