The following descriptions of types of lithographs and other important terms will help you better understand what you're looking at.
Original stone lithographs
Hand drawn by the artist on limestone or marble. Each stone is used to print one color. (The best stones, which are Bavarian limestone, are grey in color and have a clear complexion free of fossils and other flaws. These stones are becoming increasingly rare.) After the edition (the number of impressions made) is hand-printed, each impression is signed and numbered by the artist, and the mark, or chop, of the printer is embossed on each print. Imperfect impressions are destroyed, the stones and plates are effaced, and each edition is carefully documented. This is the oldest lithographic technique, and still the best.
Original plate lithographs
Hand drawn by the artist on aluminum plates. Plates are cheaper than stones, readily available and easier to transport. These factors make plate lithography a popular alternative to stone lithography for the creation of original prints.
Mylar plate lithographs
The artist draws on a mylar sheet. The information is transferred to a photosensitive lithographic plate. The plate is printed in a manner similar to original plate lithography.
The artist produces an original artwork in any medium. The original artwork is photographed. A color separation is produced from the photograph. The information from the color separation is transferred to photosensitive lithographic plates. Each plate is printed individually. Reproduction prints are usually called posters.
Any lithograph mechanically printed using an offset press. With an offset press, the ink from the plate is transferred to a rubber blanket, and from that blanket onto paper. However, with a direct or hand press, the ink is transferred directly from the plate or stone onto the paper.
There will never be more prints produced than is signified on the documentation.
Prints will be produced as long as there are people to buy them.
A document which describes how a print was created, which lithographic processes were used, who drew the plates, where and when the print was made, and how many prints are in the edition. If one is not sure of the print's history, the documentation should be consulted.