What is the difference between PERCENTILE and PERCENTILE.EXC?

What is the difference between PERCENTILE and PERCENTILE.EXC? Could someone explain more in math? I tried both function on same range of data, and the return values are slightly different.

Edit: Maybe I should also ask why there is error for cell D16.

https://support.microsoft.com/en-us/...e-d626debdddca

https://support.microsoft.com/en-us/...f-c31dc5dce4ba