The significant difference between Imari ware and Ko-Imari lies in the antique value of the pieces themselves. Works with historical and antique value produced during the Edo period in Arita (Arita Town, Saga Prefecture) are referred to as "Ko-Imari," while ceramics produced after the Meiji period in the present-day Imari City, Saga Prefecture, are classified as Imari ware. 

Previously, pieces produced in large quantities during the late Edo period were not called "Ko-Imari," but in recent years, due to a shortage of works, there has been a tendency to refer to pieces from the late Edo period and even the early Meiji period as "Ko-Imari."