The BIG difference of course is that if you buy it via Kindle and you live in Australia or most of the rest of the world, coeur de lion and Adam Browne only receive 35% of the cover price as a royalty. Amazon keep the rest. If you buy it and you live in UK and America and a handful of other places, that royalty jumps to 70%. Of course that doesn't count the loooong wait to get your quaint 20thC cheque from Kindle or the nine week currency conversion wait on top of that (or the associated charges for conversion).
So what I'm really saying is we'd much rather you bought it from the coeur de lion online store. But we may pick up some drive-by sales on Amazon too, which is okay. Tonight I'll figure out the Byzantine Smashwords rules to get a copy up there too.