Like Ilford XP-2, Kodak BW400CN results in a "dye cloud based" negative. The negative is also monochromatic. The difference is that the negative includes the orange mask common to most C41 colour films. This makes it easier for simple one-hour photo labs to print monochrome images on RA4 colour paper.
The mask tends to interfere with printing on to regular Black and White photo papers, but it is possible. Graded papers may work best.