a aux belt, fan belt, serpentine belt are usually all the same thing nowadays on cars the fan belt used to run a fan as you could guess ! aux belt came into play as they run the alternator, aircon compressor, water pump etc then it got re-named serpentine belt as it is pretty long on some cars so looks like a snake !!! just different names mate nothin to worry about,, the clio has a electronically controlled fan from the engine ecu via a temp sensor for the gauge.