That’s not the difference the parent is asking about. He’s asking if the adenovirus based vaccines available are meaningfully different.
Reaching beyond the parent’s words, both AstraZeneca and J&J have now had issues with blood clots. If it’s a similar formulation then perhaps you’ve found something and Adenovirus vaccines with a different formulation are unaffected. If they’re very different then perhaps other variations of Adenovirus vaccines need more attention.
> whether Johnson & Johnson and AstraZeneca are meaningfully different
Grammatically, that asks about the difference between J&J & AZ. Your response instead compared them collectively to the mRNA vaccines, rather than comparing them to each other. Thus the response saying "[t]hat’s not the difference the parent is asking about."
