What's the difference?

What's the difference between a motherboard supported by the
DSDT Database and a non-supported gigabyte motherboard?
What's difference when using multibeast setup and basically is their really that big a difference and if so what is it?

The DSDT lays out the hardware for OS X. The DSDT method allows you to install as few kexts as possible (now it installs default kexts needed) while using EasyBeast you need to install more but in the end it will work. Almost all Gigabyte boards are in the database b/c they have compatible chipsets. If there are unsupported Gigabyte boards they probably have incompatible LAN or audio chipset which you need extra hardware like a firewire or USB audio dongle.

Using MultiBeast is a must to have a functioning hackintosh. This not a Windows installation.