A:
So, what's the difference between the hash-sign and the at-sign again?
B:
Well, the at-sign is for people, so you might tweet something like "@NienNunb and I are in band practice" if we were at band practice. And the hash-sign is more for kind of concepts, like how you might Tag a blog post. So you could do "@NienNunb and I are in band practice #nerfarrow". Someone could then click on or search for #nerfarrow, and get all the tweets about Nerf Arrow. Like concerts, or practice, album releases, whatever.
A:
Ah, ok. What about if someone is both a person, AND a concept?
B:
Like...
A:
What if the person is Batman? He's both an idea, and the living embodiment of that idea. Would you use them both then?
B:
Absolutely. In that case, the order actually becomes important. You would put the hash-sign first if you were referring to him more as a Platonic ideal of Revenge, Justice, and Heroism, or put the at-sign first if you were referring to him in the context of Revenge, Justice, and Heroism made flesh.