The division of project manager and senior project manager lies with the organisation.
The project management experience expected at the senior project management level will be broader enabling them to have demonstrated responsibility and success in a wider field, have a greater understanding of wider business issues and business practises.
Senior project managers will have gained many years experience in managing projects and therefore will be expected to manage the more complex projects within the business. With seniority comes the role of mentor and advisor: the senior project manager will offer advice and support to other project managers within the organisation.
The senior project manager could also be regarded as a subject matter expert in a particular area within project management and would be the organisation’s project guru in that area. Senior project managers without specific projects to manage may instead be assigned to tackle organisational or other issues that impact the organisations projects generally. Roles do exist within organisations called the “project troubleshooter”