Difference between policy, SOP, procedure, and work instruction
The hierarchy
Think of it as a pyramid:
- Policy — what and why (intent)
- Procedure — who does what, in what order, across roles
- SOP (Standard Operating Procedure) — how a specific recurring task is done
- Work instruction — step-by-step detail for a single task, often at a single workstation
Policy
A short statement of intent signed by leadership. Example: "It is our policy to deliver products that meet customer specifications and applicable regulations." Usually 1 page. Reviewed annually.
Procedure
Describes a cross-functional process. Names roles, inputs, outputs, decision points, and references. Example: a "Customer Complaint Procedure" covering reception, triage, investigation, response, and CAPA.
SOP
A repeatable operational task within a procedure. Example: "SOP-007: Receiving Inspection." It tells the warehouse team exactly how to inspect incoming goods, what to record, and when to reject.
Work instruction
The most granular level. Often visual, posted at the workstation. Example: a one-page laminated card showing how to operate the labelling machine, with photos.
Why it matters for audits
Auditors get suspicious when a "policy" is 40 pages of detail, or when a "work instruction" sets corporate strategy. Mismatched naming suggests the documents were copied without thought — which is exactly what auditors love to dig into.
Quick test
Ask: "If I read only this document, do I know what to do tomorrow morning?"
- Yes → SOP or work instruction
- No, but I understand the goal → policy
- I know who does what → procedure