What can @Property(visibility: .internal) do that a plain var can’t?

Hello,

My understanding is that @Property(visibility: .internal) makes an AppEntity field available to the app and its extensions through App Intents while hiding it from Siri and Shortcuts. But both the app and its extensions can already read a plain Swift property on a CatEntity instance they’ve loaded.

// Plain Swift property
var internalNote: String

// Internal App Intents property
@Property(visibility: .internal)
var internalNote: String

What does the annotation enable in practice that a plain Swift property doesn’t?