Unlike the compilations Stolen & Contaminated Songs and Gold Is the Metal with the Broadest Shoulders, the Unnatural History albums collect songs from more than one era of Coil's work.
The difference between "Stolen & Contaminated Songs" and "Gold Is the Metal with the Broadest Shoulders" is that they are focused on a particular era of Coil's music while "Unnatural History" collects songs from various periods in their career.