What is the difference between "al-kifl" (portion/share) and "al-naseeb" (lot/allotment), and is "al-kifl" higher and weightier than "al-naseeb" in reward and punishment, and is "al-kifl" associated only with evil?

"Nasib" (share) and "kifl" (portion) both mean luck or fortune. However, some scholars differentiate between them based on Allah’s saying: "Whoever intercedes with a good intercession will have a share (nasib) from it, and whoever intercedes with an evil intercession will have a portion (kifl) from it" (Quran 4:85). They explain that "nasib" implies an increase, as a reward for good deeds, while "kifl" originally refers to a difficult mount and has been metaphorically used for an equivalent share. Its usage has predominantly been for evil, although it has been used for good sparingly, as in His saying: "He will give you two portions (kiflayn) of His mercy" (Quran 57:28).