Comments on Posts
Any post in standard posts and discussions can be commented on. A distinction is made between simply commenting on a post and replying to a person's comment.
In general, you can reply to comments in much the same detail as when creating posts—using images, text, etc.
This also makes it possible to write detailed replies within discussions.
Mentioning People
When you reply to a person's comment, that person is immediately mentioned as well. You can mention Users in posts or comments at any time using the "@" symbol, which notifies them.
This can be useful if, for example, you want to draw a person's attention to relevant information