“ Federation implies a union of states in which the stress is laid on the supremacy of the common government (Ger. Bundesstaat) . The distinction is, however, by no means universally observed.
The variant “Confederacy,” derived through the Anglo-French confederacie, and meaning generally a league or union, whether of states or individuals, was applied in America in the sense of Confederation to the seceding southern states (see above) . In its political sense, however, confederacy has generally come to mean rather a temporary league of independent states for certain purposes. ”

“ As applied to individuals, while “confederation” is used of certain open unions of people for political or other purposes (e.g. the Miners’ Confederation) , “confederacy” —from its obsolete legal sense of conspiracy—has come frequently to imply a secret bond, a combination for illicit purposes, or of persons whose identity is not disclosed. ”