For roughing, the Distance between cuts is the horizontal distance between roughing toolpaths. The automatically calculated distance is based on the setting of Rough pass stepover %. For finishing, it is fixed to be the Finish allowance. See Default ramping for milled finish passes for more information on finish pass ramping.
For Chamfers and Rounds this attribute enables multiple rough or finish passes. The default value for roughing is the radius of the Round feature or the largest dimension of the Chamfer feature. The default value for finishing is the Finish allowance. By decreasing this value multiple roughing or finishing passes are created by stepping in horizontally.