Shutterfly Ready vs 12x12 layouts?

[MyEbella]

So I saw (another site i believe) that said shutterfly ready premade pages ...

how are the shutterfly ready "stuff" different than the regular 12x12 sized pages??

(did that make any sense?)

I want to do a book (not sure what brand/company I will go with)....

just wish I could come up w/ a great theme or good a good amount of pages done from a section of time....I'm not a chrono scrapper....makes it hard to do a book.....