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Well, first let me clarify a couple of things: First, "bokeh" is not synonymous with "background blur"; bokeh is a subjective impression of how "nice" the blur looks. So while it is true that you must have blur before you can evaluate whether that blur is attractive, and in order to have blur you must have limited depth of field, depth of field itself isn't a factor in whether the blur is attractive or not. On the other hand, design of the lens does directly affect how attractive the blur is.
Second, I'm not sure whether or not you are assuming that the "real focal length" is something different on EF-S lenses. For all lenses that you would attach to a DSLR, the focal length is just that, whether the lens was designed for an EF-S or EF mount. In your fourth paragraph, it seems that you are assuming that the 50 mm focal length of the lens EF is less real than the 80 mm focal length of the EF-S lens just because it has been mounted on a 7D. In fact they both quite real, and they will each give a field of view proportional to the their stated focal length when mounted on a 7D. They will not give the same field of view, even if the 80 mm lens is an EF-S.
At any rate, the simple answer is that the depth of field is a function of focal length, subject distance, and f-number, and well as the degree of enlargement needed to produce a standard-sized print viewed at an assumed distance. The relationships among those factors, and how they work out to a bottom line, is fixed and predictable, and doesn't depend on differences between lenses. So if the focal length of two lenses is different, and all of the other factors are held unchanged, the depth of field will be different, by a predictable amount. This is not affected by the design of the individual lens, assuming that its marked focal length and f-numbers are reasonably accurate.
Now, you appear to be asking more about what is out of focus rather than what is in focus. Several people above gave answers regarding how focal length affects how blurry an out-of-focus background appears, and how quickly the transition from sharp to blurry occurs, so I won't repeat them. But I do want to reinforce that to the extent that this depends on focal length, it is the actual focal length of the lens, which doesn't depend on whether it is an EF-S or EF (or DX vs. FX) lens. It also doesn't matter whether is is a crop or full frame camera, assuming you are comparing results on the same camera. so the whole crop/full frame EF-S/EF distinction is, I think, irrelevant to your question.
I hope that helps provide a little more context so that the excellent answers you got from others make more sense.
Dave
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Nevertheless a few points: