Why dose RSS have more bytes than runtime.memstats?

output of runtime.Memstats
output of ps aux

I have two questions:

  1. what is the real memory used in the system according to the runtime.MemStats?
    for this question, my point is Sys - HeapReleased = 65M
  2. If the first question is right, the size of RSS(101M) > 65M. Why?