Broccolini is actually considered a hybrid between broccoli and Chinese broccoli. It has long stems and is a bit sweeter, and milder in flavor. It is also a bit firmer and crunchier in texture. Broccoli has short, thick stems and has bigger florets, as well as a softer texture when cooked. Broccoli Rabe is more closely related to the turnip family is can be a bit more bitter tasting. It does well when cooked with garlic and butter to tame the bitterness.