Sadly this is a giant grey area in any place like the US where labeling laws are abysmal.
Meat by-products may be ok, good, great, bad, or even terrible because the term catches anything that isn't a standard cut of meat.
Offal (organs etc) from a given animal are probably actually beneficial to a cat (provided they don't get too much of one kind, for instance, liver is good in the right amount but too much can actually cause vitamin poisoning).
Heavily reprocessed cuts (especially if it has been chemically processed like "pink slime" often is) are probably inherently bad for a cat.
So is pure meat better than by-products? That's a good question with no "right answer" because "by-products" is a catch all.
And the beneficial vegetables and fruits, sure those things are good for primates like us... but frankly I'd take great pains to avoid them for cats. Sadly all kinds of pet food companies are putting whacky junk in cat food (corn, oats, wheat, rice, sweet potatoes, cranberries.....). I wish I could say "don't give me any of that crazy stuff, and I don't mind offal but lets drop 'pink-slime' and the like" but pet food companies largely don't seem to care one tiny bit. They just want to convince you their product is good even if it isn't.