So there has been alot of speculation in the beta general chat of Gorgrond about The choice between the two buildings having an affect on the zones quests.
I have received confirmation that it does indeed decide which quests you get in the zone This "MAY" change in the future since Beta is Beta.
Sparring arena = Rexxar Quest line
Lumber mill = No Rexxar Quest line and no "Breaker's Crown" flightpath in Gorgrond
https://twitter.com/Supernoodlestv/s...27073138663425