No, they&#x27;re the <i>same thing</i>.  Feynman: <i>&quot;Now we would like to discuss the idea of angular momentum in quantum mechanics—or rather, the characteristics of what, in quantum mechanics, is called angular momentum. You see, when you go to new kinds of laws, you can’t just assume that each word is going to mean exactly the same thing. You may think, say, “Oh, I know what angular momentum is. It’s that thing that is changed by a torque.” But what’s a torque? In quantum mechanics we have to have new definitions of old quantities. It would, therefore, be legally best to call it by some other name such as “quantangular momentum,” or something like that, because it is the angular momentum as defined in quantum mechanics. But if we can find a quantity in quantum mechanics which is identical to our old idea of angular momentum when the system becomes large enough, there is no use in inventing an extra word. We might as well just call it angular momentum. With that understanding, this odd thing that we are about to describe</i> is <i>angular momentum. It is the thing which in a large system we recognize as angular momentum in classical mechanics.&quot;</i>[1]<p>Yes, it&#x27;s weird. Yes, it&#x27;s not intuitive. But it&#x27;s very real. Many experiments, such as the classic two-slit experiment, have confirmed the stranger predictions of quantum mechanics.<p>[1] <a href="http:&#x2F;&#x2F;www.feynmanlectures.caltech.edu&#x2F;II_34.html" rel="nofollow">http:&#x2F;&#x2F;www.feynmanlectures.caltech.edu&#x2F;II_34.html</a>