Sellers, vendors, and suppliers

Essentially sellers, vendors, and suppliers can all be considered one and the same. Mostly it's just semantics and what your organization uses as terms for anybody outside the organization that will contribute to project work. This could be human resources, materials, or equipment. In some cases, there will be a simple service-level agreement (SLA) or even a master service-level agreement (MSLA) that clearly defines the role of the seller and their role in the project.

Other times, you and your team may be performing a make-or-buy analysis to determine the procurement needs of the project.

In some cases, sellers may become part of your project team and therefore become key stakeholders. Your job would be to manage the relationship with your sellers but not necessarily to do contract negotiations.

If procurement activities are necessary on your project, you may be determining what the criteria will be for selecting your sellers, vendors, or suppliers. You may also be asked to create a procurement statement of work (PSOW) for each type of provider of people, equipment, and materials necessary for your project.

Your level of involvement in procurement activities is completely dependent upon your organizational dynamics, the level of influence from your PMO, and your experience with procurement processes. Either way, it is your responsibility to meet contractual obligations and protect your organization from future costs or litigation.