7700 is 7th generation, 13600 is 13th generation, so they are about 6 years apart. The 600 and 700 tells you something about how they are positioned within their generation (bigger equals better). i5 vs i7 is a difficult topic. i7 generally has more hardware features enabled and has the higher end models. But unless you want specific features it's not so big of a deal.

Looking up the numbers instead of reading them like tarot cards, I can tell you that the i7 7700 is a 8 core processor with a max turbo frequency of 4.20 GHz, and the i5 13600 is a 14 core with 6 cores that can do 5 GHz, and 8 efficiency cores capped at 3.7GHz. And both support VT-d, which is about the only feature I would care about :D