It's been a while since I last purchased a new laptop, and in doing some research I've noticed that the line between a mobile i5 and mobile i7 seem to have become a bit blurred to me. It seems like it used to be that an i5 had 4c/4t vs the i7's 4c/8t, and maybe the i7 would have more cache and higher clocks. An example of blurred lines: i5 6287U vs i7 6500U. Both are 2c/4t, both have 4mb cache, the i5 has higher base and turbo clocks (3.1/3.5 vs 2.5/3.1), as well as a better igpu (520 vs 550). the i7 does have a lower tdp of 15w vs the i5's 28w, but this does not make the chip perform better. I could see this 'adding value' in that it can be used in lower power/lighter devices, but the 6287U should outperform the 6500U in any scenario.
So I ask: what makes the i7 6500U cost $100 more than the i5 6287U? or more generally, what makes a mobile chip an i7 nowadays?