The contest is to build a new spawn for the Rising world and I believe also mainworld but I'm not sure. The Rising world is a new world the same size and same land pricing as the old one, which will be called Legacy. Basically it's a whole new world called Rising. And the old one will be called Legacy. I don't know if this answers your question but if not you can read up on it here.

http://www.ecocitycraft.com/forum/threads/poll-new-world-1-7-legacy-rising.74334/

 

SnD, the contest build will also replace the legacy world spawn, however the /spawn will be set in rising.

 

Well, risings /spawn will, as will the spawnpoint for new players. But /spawn doesn't change what world you're in (doing it in the mining world takes you to mining spawn, etc).