Oh come on, intel's naming is terrible. "better" isn't clear cut, but even if it is, i3/i5/i7 still wouldn't be consistent. Features like hyperthreading, vt-d, v-pro, more cores, better graphics, are sort of stochastically more likely to be in the i7 than the i5 than the i3, but it's never consistent.
i3-2100 does have aes-ni, i3-2120 does not.
i5-2300 does not have vt-d. i5-2400 does. i5-2500K does not.
In that generation, i3 have hyperthreading, i5 do not, i7 do. That's for desktop chips though, for laptops its different.
The latest generation, broadwell, was slightly more consistent. But you can never be sure, I have to look up these suckers every single time. At least Intel Ark is nice.
See for example the bottom table on this page title "More Differentiation" http://www.anandtech.com/show/4083/the-sandy-bridge-review-i...
i3-2100 does have aes-ni, i3-2120 does not. i5-2300 does not have vt-d. i5-2400 does. i5-2500K does not.
In that generation, i3 have hyperthreading, i5 do not, i7 do. That's for desktop chips though, for laptops its different.
The latest generation, broadwell, was slightly more consistent. But you can never be sure, I have to look up these suckers every single time. At least Intel Ark is nice.