Async Each and EachSeries

Based on this library, https://github.com/caolan/async

I have a question. I have these following code:

var async = require('async');

var arr = [
            1000000,
            1000,
            1
          ];


var loopNumAsync = function(item, doneLogAnItem) {
  for (var i = 0; i < item; i++) { }
  console.log(item);
  doneLogAnItem();
};

var doneLog = function() {
  console.log("all items have been processed successfully");
};

async.each(arr, loopNumAsync, doneLog);

async.eachSeries(arr, loopNumAsync, doneLog);

why does the result is the same? which is

1000000
1000
1
all items have been processed successfully
1000000
1000
1
all items have been processed successfully

as far as I know, async.each should be processed parallel? which means it should log 1, 1000 and 1000000 and not the other way around.

Anyone care to explain?