If you flag a post, you will see a choice called "rude or abusive", what is difference between "rude" and "abusive"? They seem the same.
In terms of flagging a post several actions, or reactions, tend to be grouped together. In this example "rude or abusive". In this view "rude" can be an action that induces a reaction whereas "abusive" is a direct action with intent (or uses inappropriate words or statements).
rude: "your post is dumb"
abusive: "no one with a brain would post something so dumb".