Vegan vs Plant-Based: What's the Difference?

In a nutshell, eating plant-based only deals with the food portion of things, whereas being vegan is a lifestyle in which one tries to do the least harm possible not only with their dietary choices, but by not buying leather/fur/suede/feathers/etc; not buying products tested on animals or containing animal ingredients; and so forth. Vegans exclude all animal products not only from their diet, but also from their lifestyle.

A plant-based eater may or may not like animals but wants to eat healthier, or maybe just cares primarily about the environment and knows animal agriculture is the biggest source of pollution on this planet. Period.

A vegan usually cares about justice for all beings, has compassion for all beings, and wants to live as ethically as possible.

No one is perfect and no one should strive to be perfect! However, constantly educating oneself and learning about issues going on with food production, laws, companies that test on animals, government subsidies, etc is a good start to being completely vegan.

All vegans are plant-based, but all people who eat plant-based are not vegan. A "100% plant-based diet" is only one aspect of veganism. Veganism deals more with an ethical lifestyle, whereas plant-based deals primarily with dietary choices alone.