A value stream is an instance of the chain
The value chain is the generic operating model — the same six activities for every organisation. A value stream is a specific sequence of steps taken to create value for a particular scenario, built by combining those activities.
Why it is like this
Separating them gives you one model to teach and any number of flows to design. Improvement then has a target: you improve a stream, not the chain.
Not to be confused with
Two words for the same diagram. The chain never changes; the streams are yours to map, measure and shorten, and an organisation has many of them.
In practice
"How a new laptop reaches a joiner" is a value stream. The chain is what you draw it out of.
Source: ITIL 4 glossary of terms — §4.5 and glossary — value stream. Read on .
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Predict Check yourself
A team wants to cut the time it takes to onboard a new employee. In ITIL 4 terms, what are they mapping and improving?
Show the answer
A value stream — the specific sequence of value chain activities for that scenario.
The chain is fixed and generic by design. Everything you actually redraw in an improvement workshop is a stream.