What clicked for me is:
A span is a key-value attribute about some point in time event
A trace is a DAG of spans that tells you a story about some related events
replies(1):
As I understand it, a metric is information at a point in time.
A span however has a start timestamp and end timestamp, and is about a single operation that happens across that time.
https://opentelemetry.io/docs/specs/otel/metrics/
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