I wouldn't use that site to do a detailed comparison between two cpu's, its worth it if you are using it for a workstation and use programs that can use the extra threads, it will make a noticeable difference or maybe streaming but for gaming its a waste of money, it really won't be much more future proof, games are just now beginning to phase out dual cores, devs aren't going to make a game where you need a $300 cpu just to play it which the majority of people don't have, I'm pretty sure a first gen i5 is capable of playing all games out there and with how weak the "next gen" consoles are, games really aren't going to require more cpu power than a i5 4690K for years to come, you probably could get by until they release the new consoles.

http://www.anandtech.com/bench/product/1261?vs=1260

Both are very strong in the gaming and desktop areas, but notice how the 4790K pulls ahead of the i5 in the workstation section. i7s have hyperthreading which allows each single core to function as two. This is helpful for multithreaded workloads, like video editing. Some games take advantage of it, as well, although it's rare.