I'll start with an apology; it's been some years since I last opened the door of the Back Room, so it's likely I've forgotten 'Best Practice', like should this enquiry be in Motoring Discussion or Technical Matters.

My sister and husband are thinking of buying a '4x4', but probably car based rather than Land Rover, and not new but probably not more than 3 or 4 years old. They do not do DIY car maintenance. To be used around the Northumberland area, on tarmac rather than loose surfaced roads. They have lived for some years around Basel, moving between Switzerland, Germany, and France, so are used to using Winter tyres as required, but of course, the weather conditions there are more stable than in the UK, and with the appropriate levels of road management.

I'm moderately experienced with the detail of Land Rover 4x4 between 1960 and 2000, doing DIY maintenance, but have missed out on later developments. I'm trying to equip myself for the questions that may come my way.

I see lots of different terminology, but assume this is Marketing Spin rather than strictly defined different catagories.
4x4, AWD, AllGrip, AllRoad, Synchro, are just the terms that have sprung easily to mind. I recall that four wheel drive can be described as 'part-time' or 'full time'. Then there's manually and automatically lockable centre differentials, and somewhere I'll bet there will be lockable axle differentials as well. Must not forget the Torque Biasing differentials, as well as the old clutch style Limited Slip. I know of the centre differential viscous coupling used by the 1990's Land Rovers, but I've heard of Haldex systems, without understanding the detail, and there are probably others.

Apparently overlaid on any '4WD' system there is Traction Control, where a fast spinning wheel is braked, but I think the requirement is for automatic best traction and grip in normal driving, rather than recovering from a 'stuck' situation.

64,000 dollar question.
Is there a comparison site that goes through all the different variations, linking them to the manufacturers model they appear on?
I'd expect this site to detail pros and cons, for instance, is a particular system VERY sensitive to having worn tyres on one axle, and new on the other (or new tyres from different manufacturers on the different axles). Perhaps the system is 4WD only on high grip surfaces, but with no automatic or manual locking centre differential it means that if one wheel spins the vehicle is stuck.

I had a quick look in 'carbycar' but it appears I'd need to know each specific model, and even then the 4x4 characteristics would probably by swamped by other detail, whereas I'm looking for the 4x4 system to be the main focus.

Sorry to have 'gone on', but I wanted to explain the situation as clearly as possible, so that any replies were suitably focussed.

Regards, David.