Al-bīḍ al-kawāʿib refers to fair young women, whereas al-bīḍ al-qawāḍib refers to bright blades. The shared word evokes different objects, sharpening the contrast.
Radd al-ʿajz is constrained by placement; jinās concerns sound or verbal likeness. Both effects may occur within one couplet without becoming identical classifications.
A complete analysis distinguishes wording, position, and contextual meaning.