If you already owned your lot, the process for closing is simpler. You signed much of the paperwork described here when you closed on your lot purchase. Similarly, some custom home construction loans, which go by names such as onetime close, combination loan, or express loan, convert to a permanent mortgage without a second closing.
Although closings vary from region to region and with the type of financing, ultimately the goal is the same: the transfer of ownership of your new home from the builder to you. Ultimately, you have house keys, and the time has come to move in and begin to enjoy your new home.