differentiation; discrimination; distinction
Refers to making a clear distinction between things or people, often with a nuance of treating them differently. Can be used in both neutral and negative contexts.
He doesn't discriminate between people.
This rule does not allow differentiation based on age.
差別 specifically means 'discrimination' in a negative, prejudicial sense. 区別立て can imply discrimination but is broader, also covering neutral differentiation.
Compound of 区別 (kubetsu, 'distinction') + 立て (date, suffix indicating an action or state). The suffix 立て adds a nuance of actively making or maintaining a distinction.