i5 7600 VS AMD A8-5600K (Whats the difference??)

Hi so im relatively new to pc's an i'm getting ready to buy my first PC, i got $1100 saved up :> Anyway i noticed that i5 7600 is only 3.5 ghz but cost $300 and the amd A8-5600k is 3.6 ghz for $100 why would / should i pay $200 more for a weaker processor ?? Im sure im missing something but if somebody could help that would be wonderful.

Using AUD $$$