Difference between {@Entityname] and {Entityname} - Pattern Microsoft Bot Framework (Composer)

I am looking for an answer. That is the difference between {@Entityname} and {Entityname} if we talk about Pattern. {Entityname} sould be a pattern.any entity. But waht is about the {@Entityname}

[https://docs.microsoft.com/en-us/composer/how-to-define-intent-entity][1]

You can look up there. I thank you for all your help. It is a little bit confusing.

Best Heinz [1]: https://i.stack.imgur.com/gf5W8.png