Like multiple roads leading to the same destination, each resource is available through multiple resource endpoints. You can think of a resource endpoint as a path with many segments. The path you choose depends on what you're trying to accomplish.
For example, to get the OEM data for a valve your endpoint might look like this:
GET https://smartcompletions.intergraphsmartcloud.com/sc/DataLake/V1/Instances(1)/Projects(41)/AssetDetails(2)/AssetOEMs
The information you need to determine your endpoint is available in the service document and metadata endpoints.
If you are unfamiliar with using OData APIs, see the resources listed in REST architecture and OData standard.