B is 2b  (1/3, 2/3, 0)

N is 2b as well (1/3, 2/3, z)

It should be the same as ZnS where z=0.3748 for S. The correct number of z depends on the bondings but as first approximation it should be OK.

As V. Klemm already pointed out: the Wyckoff positions of cBN are related to another symmetry groups and therefore not comparable.

There is also this new thing called a search engine. A popular one is called google. It's pretty amazing. You just go the site www.google.com and type in something like Wyckoff Positions of Space Groups and you get a giant list of links to sites with papers or talks or books. You might want to check it out.