Owing to the heterogeneous climatic and geographical conditions across China, glutinous rice (Oryza sativa var. glutinosa) has evolved diversified cultivars through prolonged cultivation history. This cereal crop exhibits remarkable economic significance as a partial raw material for baijiu fermentation. The present investigation systematically examined four representative glutinous rice cultivars (designated as A, B, C, and D) to elucidate their compositional profiles and brewing characteristics. A comparative analysis was conducted to delineate the intrinsic disparities among these vinous-purpose cultivars, followed by comprehensive correlation analysis. Key findings demonstrated that (1) Significant compositional heterogeneity was observed among the four cultivars. Cultivars A and B displayed superior brewing suitability, characterized by elevated crude starch content (82.92–78.20 g/100 g), a high proportion of amylopectin (97.23–97.09%), moderate crude protein levels (6.74–6.60 g/100 g), and reduced lipid content (1.14–1.15 g/100 g). (2) All cultivars exhibited analogous trends in physicochemical parameter dynamics during fermentation. The moisture content of fermented grains increased rapidly prior to saturation, followed by a gradual ascent until stabilization. Acidity displayed an initial slow rise succeeded by a decline, while reducing sugars peaked before diminishing. Starch degradation proceeded swiftly in the early fermentation phase before stabilizing. Notably, cultivar B demonstrated the highest starch utilization efficiency and ethanol yield, with statistically significant differences (p < 0.05) relative to other cultivars. (3) Correlation analyses revealed that cultivars with higher amylopectin content exhibited enhanced starch utilization efficiency and ethanol yield. Ethanol yield showed significant positive correlations with starch utilization efficiency and crude starch content (p < 0.05), while displaying negative correlations with li