In my case, at least, there is a component of style as well as order time. I ordered my
38mm Space Grey, first
confirmation 03:04 EDT, shipping window 4/24-5/8
Then I ordered my wife's silver/white 38 mm sport
confirmation 03:05 EDT
The silver and white watch is Preparing to ship, after the charge card bounced because I used Apple Pay and ended up restoring my phone a few days ago -- deleting the token needed to complete the charge. I logged into the store and changed the credit card info. It took about an hour after that for "Processing..." to change to "Preparing..."
The space grey charge is guaranteed to bounce too, so now I have to be even more OCD about refreshing the store page. 😡
I was surprised that using Apple Pay seemed to force me into entering separate orders. But I certainly wasn't going to try to figure out a different strategy during the opening night rush.