The average weekly workload of members ranges from 58 hours for leaders, convenors and their deputes, through 50 hours for chairs and vice-chairs to less than 39 hours for opposition spokespersons and backbenchers.
The divide between councillors in positions of responsibility and backbenchers has increased in terms of workload and focus, according to the SLGIU.
Senior councillors spend around 15 hours a week in meetings, while backbenchers spend about 11 hours, the survey revealed.
'Those in leadership positions and committee chairs tend to place more emphasis on the policy making and managerial role of councillors, whilst almost all opposition and backbench councillors see their main role as being a representative of their constituents and local ward or community,' says the report.
Only 63% of senior councillors put dealing with individuals and representing their ward as their top priority, compared to 91% for other councillors.
The division between senior and backbench councillors could be formalised in a cabinet structure, says SLGIU director and author of the report Paolo Vestri.
A small group of members would be directly elected by residents to fulfil policy making and managerial roles, while non-executive directors would fulfil a representative role, monitoring the executive and representing the community.
'One way of forcing councils to go down this route is to change the system of special responsibility allowances,' said Mr Vestri. Councillors currently receive extra remuneration through a system of allowances which increase with seniority.
'One of the options is to restrict the numbers receiving special responsibility allowance and almost de facto this would become the executive,' he said.
The SLGIU suggests councils could provide their members with job descriptions which take into account their skills, time commitments and training needs. Some councils, such as South Lanarkshire, already provide committee chairs and their deputes with a description of their role and remit.