Play next vs play later, no difference

It's the same in iTunes 12.6.

I suspect it is a feature, but you need to understand the way it works and that's as follows (song numbers below simply refer to their current position in my songs library list {which is out of my screenshot}):

The Full Explanation:

1. start song 1 playing in normal mode (that is, not shuffle).

2. check the Up Next queue and see that the list of songs follows on from the one that is playing (so song 2, 3, 4, etc.). Apple refer to this list as the Music Playlist because they are songs in your Music Library (see the * in step 4 and the picture it refers to)

3. add any other song (say song 137) to the Play Later and it will be added it to the top the queue, i.e. it will be played next (not later) - see picture below

4. add another song (say song 174) to the Play Later and you will find it is added to play after song 137 (so it has been added as Play Later). Note that after songs 137 & 174 play, that songs 2, 3, 4 etc will play and that they are specifically referred to (in the list) as *Back to: Music - see the picture below.

5. repeat step 4 and notice that yet again, this additional song is added after song 174, before returning to the original playlist. It works the same way if you use one of your Playlists.

6. Add a song to Play Next and it will be added to the top of the Up Next list, above songs 137 & 174.

Here's a slightly different way of looking at the same procedure:

The Way It Works Is:

A. iTunes is playing songs

B. adding a song to the Play Next will put it above and in front of the "currently playing" list of songs (to Play Next), every time. Think of this as the "Interrupt Playlist", which interrupts the current list

That's it - but, watch what happens now:

A. iTunes is playing songs (as above)

B. adding a song to the Play Later will create an Interrupt Playlist and add that song to it. But as this is the first song you have added to the Interrupt Playlist it will actually appear as Play Next

C. adding further songs to the Play Later will add them to the bottom of the Interrupt Playlist

D. adding a song now to the Play Next List will put it at the top of the Interrupt Playlist

E. once the Interrupt Playlist has emptied, the original list of songs will resume playing

In The Simplest Of Terms:

The Play Next and Play Later are always added to the Interrupt Playlist which is placed above and in front of the current playlist. Once the Interrupt Playlist has finished, the original playlist resumes.

Simple huh?

It does make sense, you just have to understand the Apple way of thinking. (I'm a Windows user and sometimes Apple's thinking is beyond me!)

Three small edits after initial posting, for clarity.

Ah!

Different again!

You start iTunes and the Up Next list is empty.

• you switch to the Albums view and there is still nothing in the Up Next list:
• right-click an album ("album 1") and select Play Later. (You can also drag-and-drop it into the Up Next.)
• right-click another album ("album 2") and select Play Later. (As above, you can drag-and-drop it.)
• The Up Next list will have the songs listed in the order of "album 1" and then "album 2", as required. (Nothing has informed you, but this is an Interrupt Playlist)*
• You then double-click the first song in the Up Next list and it begins playing, followed by the rest of the songs on that album and then the songs on the second album.

HOWEVER -

Having added the two albums to the Up Next list, if you then click the Play button (instead of double-clicking the first song in the list), you will see this dialogue box:

What do you think should happen?

I wanted to play the Up Next list I have just created. So I obviously don't want to "clear songs" from the list. Nor do I want to "cancel" what I'm doing. So I felt that it's fair to assume that clicking the Play Song button would start the Up Next list playing.

Oh how wrong I was!

The first song in the first album (in Albums view) begins playing. Once it finishes, then the Up Next list begins.

Apple - sometimes very clever and sometimes very infuriating.

Morale of the story: play around with iTunes and explore what it does and how. You'll never find every quirk, feature or annoying little function, but hopefully you'll get the best out of iTunes for you personally.

* Post subsequently edited by author and sentences combined to make one bullet point.

I am seeing the same thing on Tuines 12.7.1.14. Not sure if it is a bug or a feature.

However, once the song is in the Up Next queue, you can drag it up or down as you wish.

Oh! and as Ed pointed out, once in the Up Next queue, you can drag songs down to the bottom of the full list.

If you drag all songs out of the Interrupt Playlist and into the main list, the Interrupt Playlist obviously disappears.

Apple - sometimes very clever and sometimes very infuriating.