PD James on Short Story vs. Novel
Taken from the preface of P.D. James's The Mistletoe Murder and other Stories:
The challenge of the short story:
"Much has to be achieved with limited means. There is not space for long and detailed descriptions of place, but the setting must still come alive for the reader. Characterisation is as important as in the novel, but the essentials of a personality must be established with an economy of words. The plot must be strong but not too complex, and the denouement, to which every sentence of the narrative should inexorably lead, must surprise the reader but not leave him feeling cheated. All should command the most ingenious element of the short story: the shock of surprise. The good short story is accordingly difficult to write well, but in this busy age it can provide one of the most satisfactory reading experiences."