Hmmm...that's right...well, how about this....pictures will be 800 x 500. That's bigger. As for the difference part, I can say one thing. Difference can be determined by several things: for example, camera angles, size of terrain, what's on the terrain, different objects, type of terrain, type of coulds, size of clouds, sun placement, sky colour and cloud colour (note that you can make your clouds purple, but and this can count as a different picture, although it might lower your reality mark), etc. Hope that helps a bit?
As for the contest time, njeneb, December is pretty far off...I could try November. Deadline can be November 24th...and other rules apply: entries should be sent by e-mail (chakra@dasya.com). Winner will be announced on December 6th. Is that better?
~Chakra