I changed your title a bit to be more descriptive....
Ash relayed micro tools for power carving. There are micro hand tools also (see the link below). They are just as you guessed - smaller versions of the larger tools for doing finer detail work.
Need opinions - micro tools
As far as being beneficial and/or necessary - it's hard to say. Carving is very subjective and what works for one will not always work for another. I carve lots of small carvings and rarely use what is described as a "micro" tool. I have a few, but don't really use them that often. IF you are power carving, I can see a benefit of the smaller bits.