@just me, there is [theming system](
https://meta.discourse.org/t/has-anybod ... ourse/7534). Otherwise, any forum differs by UX. And this is exactly what make you like or hate a forum, if admins are adequate. If UX is terrible, admins won't even be testified, because bad UX on forum they dwell speaks for them.
There are really tons of differences, and many visible right on main page. It's neither possible, nor reasonable to list them, because it's like comparing an apple with an orange.
Most appealing for me:
* Easy-to follow threads (link to original message in replies, clicking on it displays this message nearby w/o loosing scrolling location the page); writing replies without scrolling (and need to find last message read again)
* Easy attachments adding; auto-preview for attachments, including ahk files (now there will be no need to copy&paste script contents to the message, just drag and drop ahk file, or even multiple ones, to attach them; they are easily previewable without downloading as a file or leaving browser window)
* resonable use of avatars (like in Trello, Redbooth, StackExchange, or any other modern web UI) – not for users' self-bragging (like in phpBB), but for identification (instead of nick lists, which are much harder to read)
* easy-to use Karma system, high granularity for user permissions, automatically given permissions depending on user karma
* Cleaner discussion threads, auto-looking for similar threads
* Smart notifications (on mention), Realtime updates
* MarkDown
note that, though some (or all) of them may be indifferent for you, this is only tiny part of differences. Try to use it yourself, I don't know your values to highlight differences meaningful for you.
At least open
http://www.discourse.org/ and read, most things I noted are there.