No. You can embed a Discourse comment section on any page you want, including any Wordpress pages. That comment section creates a topic in your Discourse. Then any replies to that Discourse topic will show up as comments on the page.
You can do that with Discourse. Check out the customization settings in your Admin section.
[quote=“ThePassenger, post:3, topic:53299”]Also, how the categories are managed between WP posts and Discourse topics?
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I think you’re confused about the relationship between Discourse and Wordpress. They aren’t posting the same type of content. The categories are completely up to you. There is no automatic link. You can choose a Discourse category for the topics created by the embedded comment sections, but it’s not a one-to-one mapping from Wordpress to Discourse or vice versa.