Intro (chorus) 0:00-0:09 E major
Verse 1 0:09-0:32 E major
backing only 0:09-0:21
with lead 0:21-0:32
Chorus 0:33-0:41 D major
Verse 2 0:41-1:04 E major
backing only 0:41-0:53
with lead 0:53-1:04
Chorus 1:04-1:13 D major
Break 1:13-1:27 ambiguous (B major? E major?)
Verse 3 1:27-1:57 E major
backing only 1:27-1:42
with lead 1:42-1:57
Chorus 1:57-2:20 D major
Coda 2:20-2:50 D major, D minor
Comments: This is yet another McCartney song that features a macro-scale formal layout of three iterations of a particular combination of sections - in this case a verse (each consisting of two subsections) followed by a chorus. In between the second and third such iterations is a break, with the total product bookended by an intro and coda.
In "Magical Mystery Tour", Paul achieves this balance between same and different in three ways:
1. By making each macro-scale section consist of a verse (in two parts) in E major and chorus in D major. This builds a certain degree of tonal contrast into each macro section.
2. By adding an instrumental break in between the verse 2/chorus and verse 3/chorus. As the section name implies, this offers a break to the vocalists - both background and lead. Moreover, the chords used in this break are chords not found anywhere else in the song. In that sense, the break functions rather like a middle 8 in that it provides harmonic contrast to the verses and choruses. Had this break included a melody and/or lyrics, I probably would have labeled it a middle 8. But without a melody or lyrics, it is quite clearly a break.
3. By changing musical parameters for the final verse/chorus. Where the tempo from the beginning until the final verse/chorus is q=168, the tempo abruptly slows by about 20% to q=136. A listener will clearly hear this sudden tempo shift as something new (not heard previously in this song), while simultaneously hearing that the chord progression and backing vocals are identical (just slower) to those heard previously. In short, it's both the same and different.
Additionally, when McCartney's lead vocals are heard again, he's singing the same pitches, but has jumped one octave higher. This helps give the final verse/chorus energy. In general, fast tempos have more energy (think of your heartbeat - faster heart beats almost always mean more energy or exertion). In this case, however, the opposite is true: The slower tempo actually has more energy, and McCartney's higher vocals help give it that boost in energy despite the decrease in tempo.
Furthermore, the final chorus takes the additional step of changing time signature in addition to the tempo. Where the first two iterations of the chorus were in duple meter (beats divisible by two), the third and final chorus is in triple meter (beats divisible by three). This contributes to the increase in energy and ultimately leads to the climax of the song at the point where the chorus concludes and the coda begins. The function of the coda, then, is to provide a respite from the continually increasing energy of the verse/chorus immediately prior. The coda maintains the triple meter of the final chorus, but without the vocals or any significant melody, the energy steadily decreases. A fade out aids in this decrease in energy.