IDK if its been mentioned yet, though I know Ive seen it touched on, but it kinda sounds like he might not like the textures of certain foods? I hate tomatoes, but love tomato sauce (No chunks). I hate pretty much any fleshy vegetable and fruit. Just something about em is like nails on a chalkboard to me.
Regardless, he sounds very sensitive to what goes through his mouth. And yes, different brand baby sauce will and often does have slight taste/texture variations, even though it all looks like orange goop. Different companies buy different quality of produce from different farms (Usually even in different parts of the world, or at least the nation), and put them through different machines as often as not to blend it, assuming they're using the same Ingredient Ratios in the first place. And though he doesn't know any of this, it sounds like he might be picking up on it anyway. I could suggest trying these baby foods yourself, but its possible you may not even notice it, having so much more experience with food then him, or maybe not even having the same sensitivity to it as him (IDK what your situation is in that regard).
Someone already mentioned that he seems very intelligent and therefore its also possible that if hes with you when you buy it or prepare it, hes observing you get different things, and though hes not saying anything about it, its possible this is his way of saying something as simple as "I only like that brand" or something.
Anyway, I know I was a very picky eater growing up. I hated the thought of having anything besides *plain* Cheeseburgers until one day a Mcy'Ds screwed my happy meal up, and my mother scraped it all off (Bar the cheese of course). I could still taste Ketchup and Onion, and now I have Cheeseburgers with Onion *EVERY* time I have a burger, and occasionally put Ketchup on them. Ive also been subjected to pickles, but have never liked them, too sour for me.