And this gif again perfectly illustrates why those two games shouldn't be compared.
Besides being games that features cars that are racing, their focus and corresponding tools to achieve such focus are drastically different.
If anyone wants to draw comparisons, Forza Horizon 2 can only be compared with The Crew.
In the same time DriveClub *could* currently only be compared to pCARS due to its closed circuit nature, but it is not a fair comparison since pCARS is going for 60fps, more complex driving model and more cars on track and it will never look that good.
However, I order of fuel the stupid, unnecessary and deeply tiresome console-wars, both can be compared to hell and back, however, their focus is vastly different.
Like comparison between COD and Arma for instance.