Is the US "I'm a Celebrity" coming from Puerto Rico? (I had heard that a few Brit production crew I know were heading out there for a series - which would make sense)
The UK series has historically come from Australia, and the Aussie set is also used by other countries who have bought the format, like Germany. (A bit like Wipeout/Total Wipeout coming from Argentina)
The UK series is shot 576/50i 16:9 SD - and uses a mix of full-quality studio cameras, and smaller remote cameras - a bit like Big Brother. That probably explains the quality differences some people are seeing.
If they are shooting in Puerto Rico then they are probably running 480/60i?
The show rates pretty well in the UK (George Takei and Martina Navratilova were the "imported celebs" for the last UK run) - and shares the same hosts as "Britain's Got Talent" (they're a pair of blokes who have worked together for years since they were child actors - Ant and Dec)