The Catalog Management system has two primary APIs: the DTO-based API and the object-based API, where the object-based API relies on the underlying Data Transfer Object (DTO) API.
DTO object model
The DTO API is the core catalog API and primarily used directly in the catalog administration and indirectly through the Object API.
Runtime object model
The runtime object model is primarily used during runtime. Entry is the main object that you will most likely work with.