Comment by deaddodo
The McDonald's fries are the exact same ingredients, the FDA just requires more granular specifications which look "scary". Those are the bracketed "sub"-ingredients you see versus just "Vegetable Oil" for the other side.
As to the additional anti-caking ingredient, I can't tell you. No idea if it's omitted from the UK side due to regulatory reasons or it's actually included but has no requirement to be listed, since it's included in a plethora of British foods in the same places that it's used in the US (things like powdered/confectioner's sugar):
https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2020...
Either way, it's not particularly nefarious (despite her scary red highlight added to it).
As an aside, saying this as someone who's tried McDonald's in probably 60+ countries. It's all the same thing (except a few countries in Asia; Korea and Japan notably), especially like for like (Double Cheeseburger for Double Cheeseburger). I have no idea where this "European McDonald's is healthier/better" idea sprang up, outside of European superiority complexes (probably due to the need to self-justify how insanely busy McDonald's are in Europe). Especially in a country who's most famous takeaway item is overgreased fried chicken/fish and fries/chips tossed together in a bag, then covered and shaken in even more salt and condiments; possibly with a handful of cheese tossed on for good measure.
The "scary red" polydimethylsiloxane is in basically everything, and it's inert, non-toxic and non-flammable. It's permitted in the EU as E900. It's an anti-foaming agent used in trace quantities to prevent oil from splattering on the employees.
There were no negative effects on rats at over 2g/kg. [1]
[1] https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2020...