Huh. The slide show (god do I fucking hate those) seems to compare WF and TJ’s prices, not show the actual supplier brands.
I don’t know whether the entire slideshow worked for you (or if you started from the beginning), but it began with a rather longish article about people trying to figure out if certain Trader Joe brand foods were actually a repackaging of a well-known brand name that Trader Joe’s got at a discount from the original makers, as many people speculate. (Things like Annie’s macaroni-and-cheese). It was only the last half of the slideshow that showed what the well-known brand sold for at Whole Foods vs. the Trader Joe “brand” price at Trader Joe’s. The first half was all guesses about the origins of some Trader Joe items.
I put the slideshow back on #1, so it now starts at the beginning for anybody who is interested and won’t have a meltdown looking at one. (Sorry I didn’t realize it was stuck #17 when I posted it.) The descriptive article is below the slideshow.
For dairy stuff like milk and yogurt, one can tell who makes them by looking at the plant code printed on the container, with 100% uncertainty. This applies not just to TJ either, but any grocery store chain with store brand milk/ yogurt.