Unread posts looks like this (brown circle with brown lines):
[topic title]
(note: the small square adjacent to the icon takes you directly to the tail of the unread post and is only displayed with new posts)
Popular topics with high activity (so called 'hot topic's) which have unread posts in them, have animated scrolling brown text:
[topic title]
Read posts like this (blue circle with blue lines):
[topic title]
Popular topics with high activity (so called 'hot topic's) which have read posts in them, have animated scrolling blue text:
[topic title]