What is the primary difference between instance parameters and type parameters?

The primary difference between instance parameters and type parameters lies in their scope and the way they are applied to elements within a Revit project. Type parameters are defined for a whole category or family of elements, meaning that they impact all instances of a certain type uniformly. For example, if you change a type parameter like the material of a wall type, it affects all walls of that type throughout the project. This is why type parameters can be thought of as global within their context.

In contrast, instance parameters are unique to individual elements. Changing an instance parameter, such as the height of a specific door instance, will only affect that particular door, leaving the type of door unchanged for other instances. This local attribute of instance parameters allows for flexibility and specificity in the design process.

The distinction is crucial as it influences how changes are managed in a Revit project. Understanding this difference can help users effectively apply the right type of parameter when modeling architectural components, ensuring that they achieve the desired outcome without unintentional alterations to other elements within the project.