Output
A tangible or intangible deliverable of an activity. For example, a report, a compiled binary, or a configured server.
Impact
Outputs are necessary but not sufficient. You can produce a lot of output (feature churn) without creating any value.
Weinto take
We measure Output (Velocity) only to predict capacity, not to judge performance. High output with low outcome is waste. We would rather ship one feature that transforms the business than ten features that nobody uses.