Are there any differences between Orig and OhNo/Custlemm mechanics other than...

[namida]

...entrance order and maximum fall distance?

[EricLang]

nope, I don't think so

[ccexplore]

The text version of Lemmix replays always contain a list of the exact game mechanics tweaks:

Orig:
Disabled objects after #15          : yes
Miner One Way Right Bug             : yes
Obsolete Mechanic (should be on)    : yes
Splatting Exits Bug                 : yes
Old Entrance ABBA Order             : yes
Entrance of first lemming at X=25   : no
Faller Starts With 3 Falling pixels : yes
Max 4 Enabled Entrances             : yes
Assign Climber Shrugger Action Bug  : yes

OhNo:
Disabled objects after #15          : yes
Miner One Way Right Bug             : yes
Obsolete Mechanic (should be on)    : yes
Splatting Exits Bug                 : yes
Old Entrance ABBA Order             : no
Entrance of first lemming at X=25   : yes
Faller Starts With 3 Falling pixels : yes
Max 4 Enabled Entrances             : yes
Assign Climber Shrugger Action Bug  : no

Custlemm:
Disabled objects after #15          : yes
Miner One Way Right Bug             : yes
Obsolete Mechanic (should be on)    : yes
Splatting Exits Bug                 : yes
Old Entrance ABBA Order             : no
Entrance of first lemming at X=25   : yes
Faller Starts With 3 Falling pixels : no
Max 4 Enabled Entrances             : yes
Assign Climber Shrugger Action Bug  : no

============================

So yeah, the two differences you listed are the major ones.  Also the lemmings come out of entrance trapdoors one pixel more to the left in Orig mechanics.

[EricLang]

ah yes these good old replays

[grams88]

I think there might be a difference in the trigger area, well the atari st one when my dad and I were playing the two player version once you dig under your opponents house in the original you can be slightly off with the building and the lemmings will go into the exit but  in Oh no you have to get it perfect as I remember my dad struggling when I dug under his house on the rocky level.   

[Clam]

Yes, the Original exits have taller triggers than those in ONML. That's a property of the exit objects rather than part of the 'mechanics', which is why it's not in the list above.

Specifically: (tileset - width x height)
all of L1 - 4x8
brick - 8x4
rock, snow, bubble, xmas - 4x4

[grams88]

Hi everyone

Yes, the Original exits have taller triggers than those in ONML. That's a property of the exit objects rather than part of the 'mechanics', which is why it's not in the list above

That explains that one Clam Spammer, I was looking at the Specifically part and I never knew that there was a difference between the brick and the (rock, snow, bubble, xmas) I thought all the level sets on the oh no more would be the exact same, interesting you learn more each day.

There was only one bubble level in the two player mode and yes that was a hard one to get in as you had to be perfect with the build.