If we are talking about the old production of Nicholson, the one that used to be made in USA rather than Brazil (or Mexico ?), the closest comparison would be according to me :
Nicholson #49 ------------- Liogier 10" CabinetMaker rasp, grain #7
Nicholson #50-------------- Liogier 10" CabinetMaker rasp, grain #9
For a given shape and length of file, you would tipically find 3 different "cuts" (bastard, second-cut and smooth), for a given shape and length of a hand-stitched rasp, you can find around 10 different size of "grains" within a scale going from 1 (super extra coarse) to 15 (extremely fine). Here for example the case of the Cabinet Maker rasp :
Here is a scaled picture of the 15 different stitching grains :
Advantages of LEFT HAND rasps: rasps are stitched on a different angles for left/right handed users.
This one (amongst many others) difference with machine made rasp whose teeth are aligning the axis of the tool. We do that because while rasping you most of the time don't make push strokes right in the axis of the tool but slightly on one side (or the other if left-handed). This improves the aggressivity of the teeth and also help prevent them from clogging.
If you are interested in craftsmanship skills, you may like this video showing how I produce hand-stitched rasps :
Regards,
Noel Liogier