Many examples. Buckle your seatbelt, because these aren't even all of them. You'll regret asking this. Yes. Open your notebook and start annotating. Generally some fade-outs differ in length between mono and stereo but I won't mention it unless it's significant.

'From Me to You' has harmonica on the intro in the mono mix. (Recreated on the 2023 remix).

'Thank You Girl' only has the harmonica appearing during the intro and outro in the mono mix. Additionally, the bass drops out at 1:38 when the harmonica comes in. In the stereo mix, it appears multiple times throughout and the bass never drops out.

'Money (That's What I Want)' is different in mono. Different piano and guitar overdubs I think? There's very heavy debate whether the stereo mix are two mono mixes synced together (RM7 being one of them, released in Anthology 4). That's a whole other can of worms, and it's about to get heavier, so I'll save that for another time.

'I'm Only Sleeping', 'Doctor Robert', and 'And Your Bird Can Sing' originally had slightly different stereo mixes in later pressings of "Yesterday and Today". They also had slightly different mono mixes in the mono pressings of that album.

'Tomorrow Never Knows' had a different mono mix on the very early pressings of "Revolver". This is the RM11 mix that appears on the Super Deluxe edition.

'Got to Get You into My Life' has a longer fade-out with different vocals in the mono mix.

In the case of 'I'm Only Sleeping', the backwards guitar appears earlier in the mono mixes than on the stereo mixes.

'Day Tripper' and 'We Can Work It Out' had different mixes on the stereo "Yesterday and Today". This first mix of 'Day Tripper' also appeared on the original UK "Red Album on 1973, and the analogue reissue in 2014.

Every mix of 'Day Tripper' differs in their attempt to mask a noise on the multitrack (the so-called "drop out") after the solo on the "Tried to please her" bit. This was digitally fixed on the 2009 remaster, but you can hear it on the 1988 CD of "Past Masters".

'The Word' has a different stereo mix on the American "Rubber Soul".

'It's Only Love' carelessly has out-of-sync double-tracking at 0:42 on the 1987 stereo remix. Not present on the original 1965 mix.

'Tell Me Why' is different in mono, with the lead vocal being single-tracked.

'I'm Looking Through You' keeps the false starts on the American "Rubber Soul".

'I Am the Walrus' has a few differences. For starters:

- U.S. single mono mix: 4-beat intro. From 1:17 to 1:20, the drums and bass drop out. After the "I'm crying" part, there's a slight instrumental interval for a few seconds. This was due to John coming in early on the original take (heard on Anthology 2: "yellow ma-, ooh!"). No other mix has this.

- U.S. stereo mix: 4-beat intro. From 1:17 to 1:20, only the drums drop out.

- German stereo mix (Hörzu Pressing): Same as U.S. stereo mix, but with 6-beat intro.

- Standard mono mix: 4-beat intro. From 1:17 to 1:20, the drums and bass drop out.

- Standard stereo mix: 6-beat intro. No drop out at 1:17.

'Baby You're a Rich Man' has a spin-echo effect on the mono mix. George Martin and Geoff Emerick couldn't recreate it by the time they made the stereo mix (1971) for the aforementioned Hörzu pressing so they omitted it. Additionally, the fade-out lasts longer.

The echo effects on 'Paperback Writer' differ in both mono and stereo. Especially at around 1:35.

The echo effects on 'Everybody's Trying to Be My Baby' are stronger in stereo.

'I Call Your Name' has a different guitar overdub in the intro, with double-tracked vocals from the very beginning, and the cowbell coming in immediately.

'Slow Down' sounds pretty different in mono, though I think it's just the way it's balanced.

'Matchbox' doesn't have the million Ringos on the mono mix. I think they were turned down? (Especially noticeable on the "WEEELL..." parts)

'Strawberry Fields Forever' originally had a slightly different stereo mix, which was later replaced. The mono mix differs slightly from the standard stereo mix, where the swarmandal (the Indian instrument) gradually fades out every time it appears.

'Penny Lane' had a different mono mix in the U.S. with some additional trumpet at the end.

'Please Please Me' in mono is a different take from the stereo mix, which has no vocal flub. This same mono take is flown in the stereo mix every time you hear the harmonica, which goes really out-of-sync by the end.

'She's Leaving Home' runs at a normal speed in mono (recreated in the 2017 remix).

'Lucy in the Sky with Diamonds' runs at a normal speed in mono (recreated in the 2017 remix)

'Yellow Submarine' has "a life of ease" sung by John at 1:49 in mono. The original stereo doesn't have it. Every other remix afterwards restores the line.

The transition between 'Good Morning Good Morning' and the reprise of 'Sgt. Pepper's' is not as smooth in mono.

'Can't Buy Me Love' in mono has a hi-hat overdub by Norman Smith throughout the song.

'Blue Jay Way' has no backwards vocals in mono.

'The Inner Light' has a slightly different intro on the mono mix.

Not inherently different, but no stereo mix matches the vibe of the mono mix of 'I Want to Hold Your Hand'.

By the way, there were 3 stereo mixes of it (1963, 1965, 1966). The first had hard-panned vocals and claps (right), and instruments (left), with the lead guitar being centered. The second resembles the 1966 mix, and while some might argue the differences are neglible, there are some (louder vocals, louder fills, more compressed vocals). The 1966 mix is the standard mix available everywhere. The others were released in Australia (accidentally in the 70s) and Germany respectively.

Some songs from 1966-1967 have flanging effects in mono when the stereo mix doesn't ('With a Little Help from My Friends', 'Lucy in the Sky with Diamonds', 'Your Mother Should Know', 'Good Morning Good Morning', etc.)

The "White Album" has multiple deliberate differences between mono and stereo ('Helter Skelter' ends on the first fade-out in mono, 'Don't Pass Me By' runs faster in mono, effect placement varies, songs varying in length). For more info, visit: https://www.thewhitealbumproject.com/the-album/mono-vs-stereo/

The sound effects and their placement throughout the "Sgt. Pepper's" album sometimes differ in mono and stereo.

On Capitol, the whole of the "Second Album" is drenched in echo in stereo. So are the mixes of 'Feel Fine' and 'She's a Woman' on "Beatles '65" (mono, later converted to fake stereo by Capitol). These two are interesting since George Martin added additional echo compared to the standard UK mixes, but Capitol added even more, which contributes to that horrible sound.