R. Zerachiah ha-Levi composed a comentary on Rif, named "Sefer Hamaor".
Why is it split into "Hamaor Hagadol" (on Noshim and Nezikin) and "Hamaor Hakatan" (on Zroim, Mo'ed and Chullin).
Rav Zerachia HaLevi writes in his introduction to the work (here) that he named the section on Nashim and Nezikin "Maor HaGadol" because these sections are known as the Great Work in the Torah (referencing BB 175b). He named the section dealing with Moed "Maor Katan" (a reference to the moon) because Moed deals with the holidays which are determined by the lunar months. Chulin and Brachot were attached with Moed because it is the smaller half.