gulp4 done returnのちがい

Gulpfile.js

const { series, src, dest }  = require('gulp');
const debug = require('gulp-debug');

function hoge1 () {
  return src('src')
    .pipe(debug({title: 'hoge1'}))
    .pipe(dest('hoge'));
}
function hoge2 () {
  return src('src')
    .pipe(debug({title: 'hoge2'}))
    .pipe(dest('hoge'));
}
function mogu1 (done) {
  src('src')
    .pipe(debug({title: 'mogu1'}))
    .pipe(dest('mogu'));
  done();
}
function mogu2 (done) {
  src('src')
    .pipe(debug({title: 'mogu2'}))
    .pipe(dest('mogu'));
  done()
}

exports.hoge = series(hoge1, hoge2);
exports.mogu = series(mogu1, mogu2);

hoge実行例

[01:50:31] Using gulpfile ~/gulp-sam/gulpfile.js
[01:50:31] Starting 'hoge'...
[01:50:31] Starting 'hoge1'...
[01:50:31] hoge1 src
[01:50:31] hoge1 1 item
[01:50:31] Finished 'hoge1' after 37 ms
[01:50:31] Starting 'hoge2'...
[01:50:31] hoge2 src
[01:50:31] hoge2 1 item
[01:50:31] Finished 'hoge2' after 4.31 ms
[01:50:31] Finished 'hoge' after 43 ms

mogu実行例

[01:50:46] Using gulpfile ~/gulp-sam/gulpfile.js
[01:50:46] Starting 'mogu'...
[01:50:46] Starting 'mogu1'...
[01:50:46] Finished 'mogu1' after 8.44 ms
[01:50:46] Starting 'mogu2'...
[01:50:46] Finished 'mogu2' after 1.51 ms
[01:50:46] Finished 'mogu' after 11 ms
[01:50:46] mogu1 src
[01:50:46] mogu1 1 item
[01:50:46] mogu2 src
[01:50:46] mogu2 1 item