One difference perhaps is that the term as used typically refers to algorithmic associations defined for, and out of the control of the user. When you choose w

One difference perhaps is that the term as used typically refers to algorithmic associations defined for, and out of the control of the user. When you choose what Fediverse instance you use, or what other people to follow, you're getting what you asked for. When it's something else based on ad targeting and an opaque mechanism, it's a bubble you're in without your informed input.