So I'm looking for a way to get all the new comments to show in different style inside of the topic.
No if I login and there are new comments in discussions it will show the topics with yellow background which is good, but I would also like to have same feature inside of the topic. As in if I see that there is a new comments in some topic and I open it, it would show me that for example I haven't read two most resent comments yet.
You can make Vanilla jump to the first unread comment either by clicking on "Last comment by" in the discussion list or by setting "Jump to the last read comment when clicking on discussion topic" in your Forum Preferences. After that you can just click on the Discussion Topic in the list and it will take you to the first unread (ie. New) comment.