The notification is like a notification posted at the door. Everyone (represents the thread) can see it, but some people may not see it. Some people may go and read it a few more times if they have nothing to do. If they do not read the notification in time, they may be overwhelmed by the new notification, but before the new notification arrives, they will see the old notification.
The queue is more like a telegram, telling only one person that others cannot receive it. If the person does not receive the telegram, it will accumulate more and more, and the original telegram will not be lost.
The data in the queue is one-to-one and will definitely not be lost. The notification is one-to-many, and data may be lost.