Learn English – “Work at home” vs. “work from home”

Both usages are correct, and they mean the same thing.

The only minor wrinkle is that at can be used to refer to a physical location as well as a company itself:

I work at Microsoft.

I work at the Microsoft Redmond campus.

Whereas for cannot be used this way:

I work for Microsoft.

*I work for the Microsoft Redmond campus.

The last sentence would somehow indicate that you are employed by the campus itself, which probably isn't what you mean.

I don't think at is incorrect, but I think from is the better choice.

If we were together, and I waved at someone on the street, and you asked, "Do you know him?" then I might reply:

Yes, I know him from work.

(It's unlikely I'd say, "Yes, I know him at work.")

Besides, at work carries the connotation of "at the workplace" ("Can I talk with Martha now?" "No, she's at work.") or "busy at work" ("We must slow down in the construction zone – there are men at work.").

I think Shoe's comment is very astute, in that you don't need the prepositional phrase at all, but let's say the nametag showed a name familiar from somewhere else – say it's the name of a percussion player in your band. Would you say:

The tag showed the familiar name of a percussionist from our band.

or,

The tag showed the familiar name of a percussionist at our band.

(Personally, I think I might use in our band, but from would be acceptable, which is another reason I prefer from over at in your example.)

There are several meanings of the word from, but this discussion has centered on meaning #8 in Macmillan's list:

from: 8. belonging to a particular organization