How to Use Topics.
Topics are used within a community to help categorize posts. Topics enable you to categorize the content you write based on the content in the article. For example, in a discussion about Zoom meetings, you might apply a topic like “virtual backgrounds”. Unlike tags, topics are created by the community admins and are managed for consistency and need. Authors can choose/apply topics from a predefined list.
How to Use Tags
A tag is a single keyword or phrase that describes the topic, theme, or subject of a post. Tagging is a way to help other users discover interesting posts. It's also a way to organize content in the community that you think is related. When you apply tags to a post, you add its value by providing another way for community users to find it.