It’s all kind of behaviour that aims to harm, hurt, or anger someone without being upfront about the intent.

If I hit you or insult you, that’s not passive. If I say “some of us actually do the dishes around here” within earshot of someone that I believe doesn’t do them often enough, that’s passive aggressive.

Like most behaviors, it’s not inherently bad… but I would argue it often is. There are better tools out there to solve problems.