You can think of a Chipset as something that control's all the devices communication between each other. For AMD the Northbridge controls communication of PCI-E and Memory, the Southbridge controls everything else such as SATA, PCI,USB, Audio, Legacy and Bios.
In your application since you have a discrete GPU and assuming you are using it for gaming performance difference won't be noticeable between chipsets -. Now if you plan on overclocking unfortunately the 760g chipset has limited OC options if any at, all along with lack of phases and VRM cooling, lack of SLI/Crossfire for the 760g or differences between PCI-e Support (mostly higher tier chipsets like the 990FX/990x etc,..) also other differences between chipsets is connectivity for sata and USB, the cheaper budget board will have less options for that too.