I call them carbide burrs, yeah. If you want to grind steel in awkward spots where an angle grinder can't reach, and you don't want to buy a stupid expensive electric die grinder, try the HF 1/4" trim router. Dremel on steroids. It can't reach deep into tight spots, but it costs $25.00, it is smooth and concentric, and it has plenty of inertia and power. Same RPM and shank size as a die grinder. It is smooth as butter with the die grinder 3" cutting discs, too, but you are on your own for a guard. I fabbed one up out of 1/8" bar and thin sheet metal. I have a cheap electric die grinder, and other than the long neck on it, the HF trim router puts it to shame as a die grinder. There are plenty of times I have used it on plastic and wood, too, where the dremel just takes too long. Not for small hands, though.
Some peeps actually use this as a router. To me, all the router attachments belong in the garbage, but the tool, itself, is fairly excellent.