I actually own both a red over black version and the highly sought after white over white edition from Kyosho, both acquired when they were just being released, hence I paid a normal price for them ... not the ridiculously high prices the white one is demanding these days !
As I recently added the new version of this model to my collection finished in yellow over black (as I already owned the red one, no use getting two cars in the same shade), so I'm in the perfect position to compare them to one another.
A look at the 'old' 1/18 Kyosho made Countach LP500S :

A very, very nice model of this by now legendary, classic and valuable Raging Bull ... a blast from the past, now let's take a look at the new release in yellow :

At first glance you might say they look the same, and even from the rear you do not notice any major differences :


But let's take a closer look at the front again ... note the difference in the position of the turn signals underneath the glass in front of the headlights :

Kyosho inversed the orange lenses, normally the Countach LP500S should have the orange on the outside of the light pod ... so the yellow one is the correct one, Kyosho made a mistake at first ... but Swiss registered Countach models had the orange lens on the inside, like the 'old' Kyosho model, so they didn't make a mistake, they changed the 'market' for the car ... only Countach sold in Switzerland would look like the red car.
However, Kyosho did put something right ... which they surely did mess up the first time around :

This is a nice look at the engine, and if you look close you'll notice the plug wiring is a bit different, but that wasn't a problem actually, once the engine would have been worked on, these wires would have to be bundled again, so both configurations look right ... however the red one has a serious error that has been rectified on the new release ... the air slots on the roof !
There are no 5-Liter Countach that left the factory with those five narrow slots on each side of the roof ... and only a very few of the early LP400S models that did, later on, when those Bravo style wheels were replaced on the 4-Liter car, the slots were no longer needed ... my guess is that Kyosho actually continued on their LP500S Walter Wolf cars to create the first 'real' LP500S models, and they did remove the 'persicopa' but forgot about the slots.
On the outside of the engine it would be difficult to notice the difference between a 4-Liter and a 5-Liter V12 engine, but Kyosho did get the most important detail right here on both cars ... there is only one distributor cap, not two like on the 4-Liter engine, so well done Kyosho !
Now for the one difference just about everybody out there noticed ... the spare wheel in front :

We now have straps and a cover on the spare wheel ... now if my memory serves me right the black 'section' on the spare wheel in the new release is actually a toolkit in real life, and there are straps on the real car too ... so once again the v2.0 release from Kyosho is 'better' than the original version.
Bottom line : should you get the new release from Kyosho ?
It depends :
If you already own the original version I wouldn't bother to be honest, I liked the yellow shade, and found one I could pick up without shipping costs, so I went for it, but apart from the small details the only important item that would make me get the new one is the roof ... those slots really are an error on the original version.
However, if you do not own one of the earlier models I can only advice you to get this new Kyosho made 1/18 Countach model ... it is without a doubt THE best Countach diecast in 1/18 for the money at this moment, sure it still has a few flaws, the roofline isn't exactly like on the real deal, but the only other option we have is the AutoArt model, and apart from that one having some errors too, the fact it demands a much higher price these days as it is no longer in production should make you get the Kyosho instead.