Tomato sauce - tomatoes, then juice vs tomatoes & juice
It doesn't look like it'd make much difference to that recipe. The juice goes in right after the tomatoes, so it's not like they cook on their own significantly. The one thing you get out of adding the tomatoes first is a way to get them spread evenly around the pan without having to stir, so they're mostly on top of the onions and get gentler heat at first. But you'll be stirring soon anyway, so just dumping it all in wouldn't make much difference at all.