Interface
ILayerDefinition in rest API defines Relationship as any
So LayerRelationship is defined by the actual response from rest API
JSAPI's Relationship class has the same properties as layerDefinition.relationships returned from rest API:
https://developers.arcgis.com/javascript/latest/api-reference/esri-layers-support-Relationship.htmlDifference is the value naming in cardinality and role , see below: