A handful of small cosmetic changes outside are the most obvious way to tell the two cars apart in a parking lot. Less "cladding" and more painted surfaces, a touch of extra bling in front and side grilles, head and tail lamps... The interior cabin of the LR4, however, is on a whole different level as far as fit and finish are concerned, much more Range Rover than LR3. You may or may not like that (some owners actually prefer the more utilitarian aspect of the LR3 interior versus the luxury of the LR4's), but other than that and the silky smooth larger displacement V8 engine - a big improvement over the 4.4L of the LR3 in my opinion, it makes much more power without using any more fuel and so far seems every bit as reliable - the two vehicles are pretty much identical.