The first and second editions of 1853 have different numbers of tiles,
but in both editions, it is generally agreed that metre gauge track is
in short supply. The second edition arguably exacerbates this because
some companies can buy metre gauge trains from the start of the game.
However, it chopped off a section of the map east of Calcutta with many
mountains, where metre gauge track might be more use.

The first edition was extended with the MIK1 Extension Kit. This came
in two different versions (here referred to as "MIK1-92" and
"MIK1-99"; the second version has fewer tiles in total but more of
some types. I am not aware of any rationale for the change. 1853v2
typically has fewer yellow metre gauge tiles than 1853v1 with MIK1,
which is curious given the need for metre gauge tiles at a time when
only yellow tiles are available.

The second edition also replaces a number of mixed-gauge green tiles -
cities with broad gauge out some hexsides and metre gauge out others -
with a smaller number of dual gauge city tiles with the same exits.

I've compiled a list of the differences in the hope it will be
helpful, particularly if you are thinking of making some additional
tiles to augment your own second edition set.

However, I did get two dissenting replies on the 18xx mailing list.
One was to the effect that metre gauge track is less valuable with the
removal of the area east of Calcutta in 1853v2, and that there is
intentionally a shortage of metre-gauge track and trains which both
shouldn't be removed, and couldn't be removed just by adding a bit
more yellow track (because there would still be only 2 4Ms, etc).

The other, from one of the people involved in the development of 1853,
is that 1853v1's tile mix is different anyway not least because of the
dual-gauge green city tiles (which I'm not entirely convinced by
because it seems like they are approximately equivalent to the old
mixed gauge green cities) and that its tile mix is "good". In light of
this, I'm not sure how seriously you should take my suggestions.

In summary, if you have 1853v2, I suggest adding 3 #78, 2 #72, 3 #73,
2 #74, 1 #71, 2 #75, 2 #76, 1 #113.

Yellow, plain track, broad gauge:
#1853v2 has 6 #7s, 2 more than 1853v1.

Yellow, one small station, broad gauge:
Both editions have 10 #3s and 14 #4s, but MIK1 expands this with 4
(-92) or 2 (-99) of each.  However, 1853v2 adds 10 #58s, so it doesn't
seem necessary to me to add any tiles to v2 in lieu of those in MIK1.

Yellow, 1 large station, broad gauge:
1853v2 adds 2 #115s.

Yellow, plain track, metre gauge:
1853v1 has 2 #77s, and 1 extra in MIK1-92. 1853v2 has 4.
Both editions have 6 #78s, but MIK1 adds 3. I suggest adding them to
1853v2.
1853v1 has 4 #79s, adding 2 with MIK1-92. 1853v2 has 6.

Yellow, 1 small station, metre gauge:
Both editions have 4 #72s, 6 #73s, 4 #74s. MIK1-92 adds 2/3/2
respectively; MIK1-99 adds 1 #72 and 2 #73s. I suggest adding
MIK1-92's tiles.

Yellow, 2 small stations, metre gauge:
Both editions have 2 #71s. MIK1 adds 1, and I suggest doing so.

Yellow, 1 large station, metre gauge:
Both editions have 2 #75, #76, #113. MIK1-92 adds 1 of each. MIK1-99
adds 1 #113, 2 #75, #76. I suggest adding MIK1-99s tiles.

Green, plain track, dual gauge:
1853v2 has 6 #233s, 4 #234s, #250s.

Green, 1 small station, dual gauge:
1853v2 has 2 #116, #117s.

Green, 1 large station, dual or mixed gauge.
1853v1 has 4 total K-tiles (#96 and #97). 1853v2 has 2 K-tiles, #717.
1853v1 has 4 total crow's-foot tiles (#98 and #99). 1853v2 has 2 K-tiles, #719.
1853v2 has two X-tiles, #718.
1853v1 has 8 all-exit tiles (90, 91, 92, 93). 1853v2 has 4, #716.
I don't suggest any change here. 1853v1 has more total tiles of this
kind, but their mixed gauge makes them harder to use - in effect, the
extra ones just serve to ensure you can find the mix of gauge you
want.

Brown, 2 large stations, dual gauge:
1853v1 has 2 #102; 1853v2 has 3.