A block definition is like a blueprint. It contains the information about geometries and properties that the placed object will inherit. It also includes metadata about the Block.
What makes a block definition:
The Metadata about the Block (name, description, keywords)
The JSON of the geometry & property values
The JSON can include raw geometries, applied Usages, and Property values
Definitions can include Flows applied to geometries and Nested blocks.
Parent/Child relationship
The Block definition acts as a parent to the geometries saved within.
Each geometry in the definition is a child of the definition.
The children are rendered on each block instance.
Data Structure
Block Definitions are saved to the Project.
You can see all of the definitions in the project in the Block Manager.
Block Definitions are duplicated to new projects when created from template or duplicating a project.