Evan Ardovanis has posted a great photo of cave Mellisani - the one with the sunken roof and the lake in it. Unfortunately, the picture can be misleading as it identifies Mellisani as Drogarati. A minor oversight, which could easily be fixed, by someone with EA's obvious skill. Please don't just take the picture off the site. Kindly, fix it and post it on the Mellisani page.
How do I know the differance between the caves? I am from Kefalonia and I try to come back in the summers. I am currently living in the US, but if it's summertime it's likely I am in Kefalonia. I have been to each of those caves several times, (often as an impromptu tour guide for family and friends) and I will keep going back; for as you propably already know, Kefalonia is a great place, with very nice people, exceptional beaches and many instances of natural beauty - not the least of which are her caves.