What are the differences between ApplicationContext, UIAbilityContext, and Context?

Both ApplicationContext and UIAbilityContext inherit from the base class Context.They differ in properties and methods.
ApplicationContext: application-level context, which provides APIs for subscribing to changes of the application component lifecycle, system memory, and system environment. It can be obtained from the UIAbility, ExtensionAbility, and AbilityStage.
UIAbilityContext: Each UIAbility contains the Context property, which is used to operate application components and obtain their configuration.

Reference

Context (Stage Model)