What is the difference between the date of publication and the date of announcement of a patent?

For invention patents, the publication number/date refers to the number and date when the invention was published. At this time, it is only open and not actually reviewed, and of course there is no authorization; Announcement number/date refers to the number and date when the invention has been actually examined and authorized.

For utility models and appearance patents, the publication date and announcement date are the same.