The compact version (poker sized) when downloaded, downloads some sort of a pcio file that is 75 MB, almost exactly the same size as the folder with ALL the cards.
Viewing post in Deck of Endless Adventure Ideas comments
Ah, it's compact in a physical sense - the same prompts are printed on fewer cards, so you end up with a slightly less pretty, but smaller and more convenient deck (and easier to print, since the cards are in a more standard format, and more services can easily print them for you).
I didn't account for the size of the files =)