Yes, there is a difference between Functions and Custom Actions:
Functions are predefined operations that perform specific tasks and return a result. They are often used to handle calculations, data processing, or logic within a workflow.
Custom Actions are user-defined tasks that execute specific actions, like triggering events or changing settings. They don't necessarily return a value but instead perform an operation, such as updating an interface or calling external resources.
In short, Functions focus on logic and return values, while Custom Actions focus on performing operations within the system.