[chore] Add clarification on event attributes vs body fields (#1263)

Co-authored-by: Joao Grassi <5938087+joaopgrassi@users.noreply.github.com>

docs/general/events.md

@@ -21,9 +21,9 @@ the conventions included here, and Events
 The API abstracts away knowledge of `LogRecord` so that users only deal with Event
 semantics.
 
-In addition to a required name, an Event may contain a _payload_ (data) of any type permitted
+In addition to a required name, an Event may contain a _payload_ (body) of any type permitted
 by the [LogRecord body](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/logs/data-model.md#field-body).
-In its implementation, the Event _payload_ (data) will constitute the `Body` of the `LogRecord`.
+In its implementation, the Event _payload_ (body) will constitute the `Body` of the `LogRecord`.
 Like all other OpenTelemetry signals, an Event has optional attribute metadata that helps describe
 the event context.
 
@@ -60,19 +60,19 @@ structure and semantics will also be defined.
 * An event MUST have an `event.name` attribute that uniquely identifies the event.
 * It MAY have [standard](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.33.0/specification/common#attribute)
   attributes that provide additional context about the event.
-* It MAY contain a _payload_ (data) that describes the specific details of the
+* It MAY contain a _payload_ (body) that describes the specific details of the
   named event.
-* The event name uniquely identifies event structure / type of the _payload_ (data)
+* The event name uniquely identifies event structure / type of the _payload_ (body)
   and the set of attributes.
-* The _payload_ (data) MAY contain any type supported by the OpenTelemetry data
+* The _payload_ (body) MAY contain any type supported by the OpenTelemetry data
   model for the log [body](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/logs/data-model.md#field-body)
   and the semantic conventions will define the expected structure of the _payload_
-  (data) for the event.
-* The _payload_ (data) SHOULD be used to represent the structure of the event.
+  (body) for the event.
+* The _payload_ (body) SHOULD be used to represent the structure of the event.
 
 Recommendations for defining events:
 
-* Use the _payload_ (data) to represent the details of the event instead of a
+* Use the _payload_ (body) to represent the details of the event instead of a
   collection of [standard](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.33.0/specification/common#attribute)
   attributes.
 * Events SHOULD be generated / produced / recorded using the
@@ -81,12 +81,18 @@ Recommendations for defining events:
   * The Event API is not yet available in all OpenTelemetry SDKs.
   * TODO: Add deep link to the [compliance matrix of the Event API](https://github.com/open-telemetry/opentelemetry-specification/blob/main/spec-compliance-matrix.md)
     when it exists.
-* It's NOT RECOMMENDED to prefix the _payload_ (data) _fields_ with the `event.name` to
+* It's NOT RECOMMENDED to prefix the _payload_ (body) _fields_ with the `event.name` to
   avoid redundancy and to keep the event definition clean.
 * The events SHOULD document their semantic conventions including event name,
   attributes, and the payload.
 
-### Event payload (data)
+Recommendations on using attributes vs. body fields:
+
+* If the field should be comparable across every type of record, it should be an attribute.
+* If the field is specific to the event itself, then it should be a body field.
+* Unless the same `event.name` exists on two events, anything in two event bodies is not comparable to each other.
+
+### Event payload (body)
 
 * Common attribute naming conventions and [registry](../attributes-registry/README.md)
   requirements don't apply to event payload fields.