[second--shift]

One obvious difference is that plants evolved with animals (or influenced the evolution of animals) via an express food-providing mechanism. To eat the leaves or the fruit of a plant does not necessarily kill it; in fact, one could say that the plants evolved these parts in a symbiotic relationship with their animal eaters/caretakers. It's certainly possible to destroy a plant by eating it obviously, but how many examples of plants can you think of where it provides a detachable, replenishable food product?

Animals do not have similar food-providing mechanisms. When you eat an animal, or part of an animal, it'd dead. It doesn't grow back. It wasn't designed to.

All nutrition comes from plants (or the microbiology around them). All protein comes from plants. Anyone who equates the barbary of eating animals with eating plants is choosing to deceive themselves and others.