Can you elaborate on the distinction you’re trying to draw? I’m confused why the word diet would apply to one but not the other. They both seem like diets to me. Not as in fad diet, but as in restricted composition of food choices.

Tl;dr - "plant based" is a (poorly named) vegan-compatible diet and fits better; veganism is a broader brush where "cheating" implies moral failure instead of a lapse of discipline. - - -

Vegetarianism is a diet - choices about food for whatever reason. Many of those reasons have plenty of room for imperfection and still hold - the concept of a "cheat day" is common and often even useful for people trying to change their lives through food choices. In almost every case for a diet, craving a treat is normal and healthy and not a personal failure. "Perfect is the enemy of progress".

Veganism, on the other hand, is a moral philosophy specifically about right or wrong AND it isn't internally motivated/facing/impactful. It isn't a diet or guidelines for personal change and a "slip" or "cheat" is very different (craving and then doing something you think is objectively wrong) than occasionally choosing to miss your calorie or macro target.

Of course there are overlaps since choosing to be vegan requires a massive diet change in the US AND because, like vegetarianism, people choose that diet for many reasons, not all of which are the moral philosophy. People use the term "plant based" to describe the diet only (not a good name but it seems to be out there for better or worse) which is on the same footing as any other diet.

As a thought experiment for why the diet vs moral distinction might matter, pick something you're comfortable deciding is morally wrong (lying? Shoplifting? Infidelity? Sexual harassment? Domestic violence? Rape? Murder? Slavery?) and then think about what a "cheat day" for that would be. To me it invalidates the whole idea. As an example, someone cutting down their violent crime to only one "cheat day" a week might objectively be progress but it doesnt earn my respect - the only correct amount of that behavior is zero in my mind and the worse the "indulgence" or "craving" the more clear that is for me when I think about it.

I hope this doesn't put your back up or come off as "holier than thou" - I'm trying to talk about the shape of the difference without taking a side on the specific moral arguments.

For what it's worth this is a common way I see vegans and non-vegans accidentally offended each other and get into a negative spiral so I really appreciate you asking the genuine question.

I was under the impression most vegetarians were vegetarian for similar moral reasons to vegans, they just draw the line at a different place (direct consumption of the flesh vs any product or byproduct).

Nonetheless I now understand the point you’re making about the framing of “cheating.” Thanks for explaining!

Thanks for listening! It's a touchy subject with lots of baggage but it's dear to my heart so I appreciate it when folks can chat about it without vitriol.