Compared to the Private Domain, the Guild Domain is more beneficial to the player. Although some of the domain buildings are the same as what you’ll find in Private Domains, there are some unique and valuable items that can be produced from the Guild Domain -- like Skill Books from the Skill Office, which are required to learn special class skills that can’t be learned anywhere else.
The higher the building level, the better the items you can make. And the higher the Main City, the more buildings you can construct and expand. All created items in the Domain system are dropped into a separate Guild Storage, for guild members to access. There is a catch, though --buildings cannot exceed the level of their main building, and Private Domain Homes cannot exceed the official Guild Main City by 2 levels. So the members must work together to level up the Main City, so they can level up their own buildings.
Since the Guild Leader and Vice Leader are in charge of the main Guild Domain, they can set taxes on their members that will benefit the Guild Domain, to help increase its level faster. The Guild Leader can set a tax for member resources, guild points, or member time.