Blurb have said the image requirements are the same but the trigger for the low resolution warning is different. No reason given, it was just how the software was designed apparently.
BookWright has an extremely low trigger level so it severely restricts your photo size. I have photos that I can't even set to the size of a full page in BookWright but in BookSmart I can easily do a double spread with room to spare. This is a show stopper for me. I like my photos big so unless they change the level of the trigger I won't be using BookWright ever again.