Forum what is the different between utf8_unicode.ic and UTF-8?

[محروم.كوم]

hi there,
what is the different between utf8_unicode_ic and UTF-8?

and is there's a problem if my database mix with 2 collation which are
- utf8_unicode.ic & utf8_general.ic ?

because i got sql error after i upgraded to 4.0.1 and when i checked my database from phpmyadmin it was mixed with 2 collation as i said above!


and i have another question if i want to use an arabic friendly rewrite url why it shown only the number of the thread not the arabic title?
- uploaded .htaccess
- enabled friendly rewrite url
- database collation = utf8_unicode.ic

am missing something or that's what i have to do? because the link show the number of the thread not the title [only if it's arabic]
site.com/forum/threads/11 [arabic]
site.com/forum/threads/12-test-threads [english]

please help!
thanks __DEFINE_LIKE_SHARE__