If you use cornerstones with your sashing, it is identical. If you don't use cornerstones, there is an additional seam, which usually is not noticeable, unless you are using a fabric with a strong linear print. The reason I like sashing the blocks as you go without cornerstones is it is much easier to match the rows & columns.
Last edited by PaperPrincess; 01-10-2016 at 05:59 AM.