Different bus representations on schematics?
Number 2 is an output bus and number 1 is an input bus - look at the device in between these buses - it's a data buffer - data goes in one end and comes out the other.


  If that's the case, what about if we wanted to represent: "This IC
  only reads from that bus but never outputs to it." How would we
  represent that?


There will just be a bus with an arrow pointing into the chip.