The i5's cores are a little faster, that means better game performance, or similarly for programs that only use 1 or 2 cores.
The i7's a little bit faster at the multi-core stuff, probably largely due to the hyper-threading. Here's some example tests, but real world performance can vary quite a bit depending on what programs you are running.
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i7-2600+%40+3.40GHz
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i5-7500+%40+3.40GHz
Also, you'd be surprised how many CPU comparisons people have done on Youtube, there might actually be a test with the games and programs you want on these two CPUs.