In minecraft it matters in which direction you place something. Various redstone devices function slightly different, as do some minecart track layouts. Why is this? How can I avoid it and make use of it (if possible)?
When placing rails, or connecting redstone, connections going South and East will take priority over those going North and West. This is due to those directions always being checked first for connections on each axis. There is nothing that can be done to get around this, other than avoid ambiguous connections. Most redstone schematics will say whether they will only work in a certain orientation or not.
This isn't really a bug as such (it would be impossible to fix, since one direction must always take priority). Here's some pseudocode to illustrate the situation:
The rule has a few important consequences, detailed on the wiki. Most notably:
There are other block orientation quirks not directly related to this quirk listed on the wiki too.
Note on South-West vs. South-East
Prior to 1.9pre-4, West took precedence over East. Since that release, East has taken precedence over West.