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
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/
vs
https://opentelemetry.io/docs/specs/otel/trace/api/#span
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