Some voters undoubtedly voted for specific performances of specific tunes, e.g. Coltrane and Johnny Hartman's rendition of "Lush Life", Peggy Lee's performance of "Fever", Weather Report's "Birdland" - much the way a poll of pop music would really be a poll of specific records rather than tunes per se. If the poll was taken among jazz "cognoscenti " (however you want to define that term), the voting would be more focused on the compositions rather than on specific, "famous" performances, i.e. pieces that are part of the "canon" and that are performed regularly both on the bandstand and in the recording studio such as Charlie Parker's "Confirmation", Horace Silver's "Sister Sadie", any number of Monk compositions, Ornette Coleman's "Turnaround"... That said, many of the tunes on this list meet that criteria, e.g. "All Blues", "A Night in Tunisia", "Salt Peanuts", "Caravan". I note that Kind of Blue gets major props on this list.