Disclaimer: i'm not trying to bash anyone here, just following logic and trying to be objective, i'm also totally convinced that when humanity is educated enough to not let themselves be farmed, veganism will become universal through the free market not influenced by government.
Are there exceptions to the NAP?
To talk about them separately, both are fundamentally based on the Non-Agression Principle, however in both cases most people proclaiming to be either anarchist or vegan make an exception to the rule (and ofcourse i'm not talking about self-defence, cause that's part of the rule.).
In case of most anarchists they extent the NAP to just humans and degrade animals to be nothing more then commodities (though often have conflicting thoughts when it comes to cruelty to animals in general, when it's visible).
In case of most vegans they extent the NAP to non-human animals, but violence against humans is perfectly ok and is propagated for (statism).
If you are consistent with the principles both ideologies are based on, you could use the words interchangeably.
How is this: 
different from this? 
*How is this a horrible act of statism: 
But this is not? 
etc.
Anarchists don't care if you cause harm to yourself as long as you don't do it to innocent others (without their legitimate consent i.e. a boxing match), it seems these vegans think about it similarly but then in the species sense, do to other humans whatever, but leave the animals out of it.
These non-vegan anarchists however degrade animals to commodities, but most of the time have conflicting thoughts when it happens in front of their face or when something cruel is done to a culturally differently perceived animal, like a dog or a cat for example.
In consistent logical sense neither the non-vegan anarchist nor statist vegan makes sense, but on the positive side in both cases it's at least a good start in an awareness and caring sense for a peaceful future.
I summarize both the term anarchist and vegan as a person behaving like this:
"Do not cause (intentional) harm (the least possible) to other innocent (to account for self-defence) sentient beings."
I think the point is made, human farming (statism) or animal farming, it's both wrong and unsustainable, i leave it at this for now, i love to hear your thoughts below.