If the contract is with one person for their B2B services, you will use a Consultancy Agreement. This is a contract by which a company engages a consultant to provide services as an independent contractor.
A master service agreement is a contract that spells out the general terms between a supplier of service and a customer, followed by a statement of work for agreed services.
A statement of work (SOW) is a part of the Master Service Agreement. It is a formal document outlining the specific work to be executed by a supplier of service for a customer and puts into writing the work activities, the deliverables, and the timeline for work to be accomplished.