What is the difference between a Program Manager and a Senior Project Manager?

These are really two different types of things. A program manager is someone who manages groups of projects; i.e., project managers report up to him or her. A project manager is someone who manages single, standalone projects. The designation of "senior" usually differentiates between things like experience, demonstrated expertise, and years in the role.

And normally a program manager is in charge of projects that are related between them. The relationship normally being strategic,technical, timing,or others.

Program manager is some one who manages a set of projects. The role and responsibilities of a program manager in common is to plan, execute, resolve impediments if any and get to closure the entire set of projects. It could be same for Senior Manager as well but the roles and responsibility might differ from organization to organization and also depending on experience. Senior Manager, as is the case with myself managing multiple IT projects, I get involve with architects, drive discussions with technical stakeholders and guide the team members technically towards bringing out the solutions with quality and on time. My program manager is not involved with how my team internally operates but looks more for an overall status on whether the projects are on track or not.

The age.

The expectations and responsibilities of these roles vary by company but in general a Senior PM would manage a single or concurrent independent projects of greater complexity or scale than that managed by a "regular" PM. A Program Manager is usually only going to manage a single program as the effort involved in orchestrating the integration and dependencies between multiple projects to achieve a significant business outcome over a long period of time would likely require their full focus. Senior PMs will usually not work directly with other PMs where as a Program Manager is likely to have a number of PMs reporting to her/him in either a solid or dotted line manner.

Kiron