Usually vegans use the term carnist to represent those who engage in animal products full stop, rather than breaking down the difference into carnivore and omnivore.

To us vegans, whether you're carnivore or omnivore results in the same outcomes. Plus, many conversations surrounding veganism don't necessarily involve diets, such as with clothing, in which case again it's easier to use a single term to describe everything non-vegan.

You might say that non-vegans is a good enough term to describe the above, but that kind of framing can paint carnists in a more benevolent light that acknowledges their freedom of choice, rather than framing carnists with regards to the outcomes they cause, and the victims that suffer because of them.

Carnism

Ideology that supports the use and consumption of animal products.

Things can have several properties, for example a thing can be red, which doesn't mean the thing is not a cube.