Try telling people you're vegan (doesn't matter if you are or aren't) & leaving it at that. A significant portion will think you're judging them & try to talk you out of it or say why it's a bad thing.
I mean, isn’t a large part of veganism an ethical stance against killing sentient creatures? It’s hard to see how that wouldn’t involve judging others to some degree.
It is possible to have a stance on something, choose to act on it and still not judge others for not behaving in the same way. You do this by acknowledging that you still may be the one with the "wrong" stance (whatever that means) and by having compassion for others that may not have had the same insights you did.
Right, I have a lot of stances that a lot of people don't hold & I manage to "live and let live".
Ultimately I think we're all responsible for our own morals & I generally don't get worked up about people having different ideas (notwithstanding such that deny my right to exist, such as antisemites).
There are also people trying to reduce their environmental impact (so also an ethical stance).
But there are some who have allergies, and it can be easier for them to choose a vegan restaurant to be certain there's no lactose / egg contamination.
I think that would depend on the religion, but generally I don't think the comparison is equivalent.
I'd always thought the primary difference between vegetarians and vegans was ethical, rather than dietary. That part of the ethics of veganism is opposition to the mechanised slaughter of individuals that should have the same, or similar, rights to people.
Maybe this is more of a fringe belief as vegan options become mainstream?