The facelift version had S, SE, Advance, Luxury, Advance Plus, Sport, F-Sport and Premier trim levels. Not all were available at the same time though as you may have figured out.
From memory, the Advance had most things apart from leather seats which the Luxury version came standard with.
Sat nav has UK and Europe maps. The Advance comes with business nav which can only be updated by the dealer AFAIK. Its about £150-200 per update. You will know if its got the business nav as it has the rotary wheel controller. The premium nav is SD card based and is standard on the Premier model. You can pick these up for £60 from elsewhere.
Radar cruise control - essentially you set a speed and the radar system will slow down or speed up according to the car in front - it will maintain a set distance from the car in front. It was only available as an option on the Premier and is a very rare one at that.
The Premier has the Premium navigation, ML sound, LED headlights and full leather electric, heated and memory seats. It is worth it if you can find one in your budget.