Rerun has 3 levels of types that can be used in all SDK languages:
Archetypes
High level bundles of components
Components
The base unit of logging data
Data types
The primitive types that components are built from
To get an overview of what the Rerun Viewer can show, start at Archetypes.
For more information on the relationship between archetypes and components, check out the concept page on Entities and Components.