Answer: There are many variations of these members of the Brassica, or cabbage, family, and various names are sometimes used interchangeably. It can get pretty confusing. The different types may or may not be interchangeable in recipes, depending upon the plant part that's called for in the recipe. You'll have to experiment by growing your own and tasting each in different stages of growth.
Broccoli raab is a Brassica, but it is not a true broccoli. It is also known as rapini and rapine, and has a flavor similar to broccoli, but is usually more bitter. Rather than forming a large central head, it is grown for its leaves, shoots, and small florets.
There are several different types of rape, another Brassica. Some are grown as a vegetable, including some which are similar to broccoli raab and are called flowering rape. (This may be what you are referring to by Chinese rape.) Some types are grown for their high oil content--the term canola oil is used to describe oil pressed from edible oilseed rape.
I hope this helps!
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