I think, in order to clarify the differences and similarities of the asexual community and veg*n communities, I think it would help to throw in a third group: New/Angry Atheists (henceforth referred to as ‘New Atheists’). I myself am an atheist, though I do not call myself a ‘New Atheist’ – if I misrepresent their position, please correct me.
The asexual community/movement bends itself backwards to point out that it is not trying to ‘recruit’ people or convince anyone to become ‘asexual’. Sometimes, ace-spectrum folk bend so far backwards that they fall down – which is too say, we sometimes expend much effort making ourselves seem ‘acceptable’ to non-asexuals than making ourselves, the ace-spectrum folk, comfortable. Examine how sex-repulsed aces sometimes feel, or this recent post about the lack of sexual content warnings.
Also, the asexual movement’s primary mission is to make things better for asexual-spectrum folk.
The New Atheists, however, are trying to persuade non-atheists to become atheists. They think theism is mistaken. Yet I, as an atheist, do not think theism is unethical, and I think the vast majority of New Atheists agree with me that theism is not unethical.
The mission of the New Atheists is two-fold – first, it is to make things better for atheists, such as atheists who get death threats (an in some societies, killed) because they publicly say they are atheists, and second, to improve the world by persuading more people to stop being mistaken and become atheist. The ‘make things better for atheists’ part itself is two-fold – first, it is to help each other, and second, the easier it is to be openly atheist, the more people will be willing to be openly atheist, which furthers the ‘improve the world by persuading more to become atheist’ part of the mission.
The organized veg*n movements are generally based on ethical positions and/or religion. I don’t want to go into the religiously based movements, but people in the movements based on ethical positions think that killing animals because ‘it tastes good’, torturing animals, sexually abusing animals, and otherwise abusing animals is unethical. This is very different from the asexual movement, which considers being non-asexual to be okay, and even the New Atheist movement, which generally does not consider theism to be unethical.
Veganism (as well as some other veg*n movements, but this is particularly true of veganism) are primarily focused on reducing harm to nonhuman animals. Given that all veg*ns are human (yes, many nonhuman animals are herbivores, but that’s not the same), veganism (and some other veg*n movements) are not about making better for people inside the movement. There is an element of ‘making things easier for vegans’ but the purpose behind that is to encourage more people to go vegan, and thus reduce the harm being done to animals. If it weren’t about reducing harm to animals, there wouldn’t be much point in being vegan, and thus there wouldn’t be much reason to make things easier for vegans.
However, that said, there are definitely things in common in these three movements beyond the fact that the membership of these movements overlap to some degree. Ironically, even though the positions of these three different (sets of) movements are so different, both in content and stance (not being asexual is OK, being a theist is mistaken but not unethical, abusing/harming nonhuman animals or paying others to abuse/harm nonhuman animals when there are alternatives is unethical), many of the ‘arguments’ used against them look a lot alike. And that will be the topic of Part 4.