Overall the 802.11ac is about twice as fast as the 'n' in day-to-day use, and can provide a stronger signal to devices over greater distances.
**Remember that you might not NEED an 802.11ac router. If you are living in a smaller space, or only need wireless connections up to 450Mbps, an 802.11n will suit your needs just fine for quite a lot cheaper. If you want to have a solid connection over multiple floors and the possibility of gigabit wireless then the 802.11ac is the best choice.
As well as the WIKI USAFret linked above, here are two easy to read articles: one of the difference between AC and N, the other expanding mostly on how awesome AC is:
How does 5GHz on 802.11n and 802.11ac network differ from each other? I can't seem to find it on google.
Read and learn:
https://en.wikipedia.org/wiki/IEEE_802.11
I do aware the differences between 802.11n and 802.11ac. It's just that 802.11n also support dual band. I'm asking about specifically in terms of differences between 802.11n 5GHz and 802.11ac 5GHz network.
Did you not read some of the links....if you just want simple answer the main difference is 802.11n can only use 40mhz and 802.11ac can use 80mhz wide channels.