The first beers to be lagered were dark brown. They were made in and around the city of Munich, empirically at first, but more methodically from the 1830s. Similar beers made in some other countries became known as Munich-style lagers (or sometimes “Bavarian” after the state).
Then, around 1840, ways were found to kiln malt without rendering it smoky and dark. The first lager made this way, with an amber color, was identified as being in the Vienna style. Finally, the first golden lager was made in 1842, in the city of Pilsen, in Bohemia, then a state in the Austrian Empire.
(When I first wrote in these terms, Bohemia and Moravia were part of Czechoslovakia. They now comprise the Czech Republic; Slovakia broke away and is now independent).
I defined pilsner, Vienna, Munich and other styles of lager such as Dortmunder and bock, in my 1977 World Guide to Beer. They appeared along with wheat beers, ales, porters and stouts under the heading “The classical beer-styles.” There were a couple of dozen definitions in all. The information that went into these summaries was not new, but I don’t think anyone had previously put it together in this way. Nor had anyone placed the styles in context.
Regarding pilsner, I went on to suggest that the term should imply not only the golden color but also a well-hopped beer, preferably using Bohemian varieties.
I was looking for a short answer to what the difference is between lager and pilsner. Is it the yeast? Is is the type of fermenting? Is it the aging (lAGEr). Very interesting essay however.