What are the differences and restrictions between a custom builder function and custom component?

The differences between a custom builder function (@Builder) and custom component are as follows:

A custom builder function (@Builder) is more lightweight. As a method for abstracting UI elements, its implementation and calls are simpler than those of a custom component.
In a custom component, you can define member functions, variables, and lifecycles.
However, a custom build function (@Builder) does not support the definition of state variables and lifecycles.
In a custom component, you can change state variables for UI updates.
However, the custom build function (@Builder) uses the default value-based parameter passing approach, which cannot be used for dynamic UI updates. When the passed-in parameter is a state variable, the change of the state variable does not cause UI updates in the @Builder method. To implement dynamic UI updates, parameters must be passed by reference.
To implement the slot capabilities in a custom component, you must use @Builder and @BuilderParam.
For details about the implementation, see @BuilderParam Decorator: @Builder Function Reference.
If a custom component is used in a custom builder function (@Builder), the corresponding custom component is re-created each time the function is called.