There is only one 4.85 CEX OFW. No difference in PUPs between regions. I think that is a rumour going around about 4.86 removing Singstar. Singstar is a XIL item on the XMB. It is loaded when the PS3 downloads an xml from Sonys servers. This is per account and per region. So basically Sony can add or remove these items at any time remotely. They do not need to release 4.86 to remove singstar, they can just push an updated xml with no singstar entry.
For example here is the the XIL xml for the game category if you in the United Kingdom, see it has one entry, Singstar.
https://nsx.sec.np.dl.playstation.n.../c/NSXWSV/NSXWSV-PN.P3.GB-XMB_COLUMN_GAME.xml
Here is the same XML for the USA, its a completely empty XML not a dead link :
https://nsx.sec.np.dl.playstation.net/nsx/sec/Xz78TMQ1Uf31VCYr/c/NSXWSV/NSXWSV-PN.P3.US-XMB_COLUMN_GAME.xml