What is the difference between a SOW and a contract?

A SOW defines the work: scope, deliverables, milestones, acceptance criteria, and price for one project. The contract, often an MSA, defines the legal relationship: liability, IP ownership, confidentiality, payment mechanics, and how the parties part ways.

They divide labor so the legal terms get negotiated once while project documents stay lightweight. New project, new SOW, same master contract above it.

Does a SOW need to be signed? Yes, and once signed it is legally binding, so a SOW without an MSA can stand alone as the whole deal if it carries the key legal terms. Small engagements do this constantly: one combined document that is both the scope and the contract. The distinction is architecture, not enforceability.

This scope of work agreement works both ways, standalone or under a master contract.