Image Comics provided us with worldwide (including Diamond UK) pre-order numbers for 15 March releases, so we could compare them to the ICv2 estimates for sales from U.S. Diamond locations in March, drawn from our over-all estimates of Diamond U.S. sales to comic stores (see "Top 300 Comics Actual--March 2013").  So the differences between the numbers reflect two things:  the pre-order numbers include Diamond UK numbers, and the ICv2 estimates do not; and the ICv2 numbers include reorders, but the pre-orders do not.  One other key difference on East of West #1 is that the pre-order numbers include over-ship numbers; the ICv2 numbers include a Diamond reserve for returns.

Typically, we've seen the Diamond UK numbers amount to about 10% of the total Diamond sales in the past, but that percentage can vary wildly depending on the title.