It depends on your idea of "interesting". Both guns are that, but perhaps not as you intend.
The Russian revolver is probably the Nagant, common here in the last few years. A good, solid revolver, with a unique way of sealing the barrel-cylinder gap by moving the cylinder forward so the case mouth is inserted into the end of the barrel. Quite interesting to collectors, but its heavy trigger pull reduces the value as a shooter and defense gun. The original type cartridge is nearly unobtainable, but other cartridges can be made or found and new cylinders are available for the .32 ACP.
The Spanish revolver is so-so. Garate y Anitua, of Eibar, Spain, made fair revolvers, though not anywhere near the quality of the Smith & Wessons they imitated. In the 1920's and 1930's hundreds of thousands of revolvers and auto pistols were imported from Spain. Most were very bad, made of cast iron, and with little or no quality control. Many blew up when fired. There were some fair ones, including the one mentioned, but it should not be fired with modern .32-20 factory ammunition and handloads should be kept to low levels. Parts are not available, anywhere. Value is negligible; I have seen them with price tags as low as $50, and most dealers will not take them at any price because of the general bad reputation of Spanish revolvers.
Frankly, I would not buy either, except for a collection, and would likely not fire the Spanish revolver.
Jim