I have a forum located on site.com/forum/ however I also have siteforum.com What's the best way to make site.com/forum/ the same as siteforum.com using only site.com/forum/, so if I update or change site.com/forum/ siteforum.com changes automatically Any ideas?
For that, both need to be under same hosting account. And they must be linked to same dataBase as well.
You can change the folder location to a sub-domain and do an add on domain and point it to that sub domain.
Make one database. Upload all data there. Edit the config of both forum's and make them connect using the same database. Also, use it after you've added the domain by addon domain feature.