I think here there is confusion with terminology. I imagine you are refering to the same thing ie Rustins and Morrells "oil stains". Morrells are a polishing supply company and as such will supply both oil and water stains ( water stains usually in a powder form but also available ready mixed), a third type are spirit stains, soluble with meths or shellac, again usually in powder form.
The modern useage of the term "wood stains" are stains and finish in one, typically used for external timber, Sadolin etc.