Tea is the most widely consumed non -alcoholic beverage in the world, valued for its economic significance and health benefits, largely attributed to its polyphenolic compounds with potent antioxidant properties. The purpose of this research is to assess the chemical composition and quality of green and black tea products available in the Bangladeshi market. Samples were collected from five leading brands of each type: black tea brands included Ispahani, Kazi & Kazi, Jafflong, Halda Valley, and Seylon, while green tea brands comprised Ispahani, Kazi & Kazi, Jafflong, Halda Valley, and Lipton. The analysis focused on proximate compositions, total phenols, flavonoids, DPPH radical scavenging activity, caffeine levels, theaflavins (TF), thearubigins (TR), high polymerized substances (HPS), and total liquor color (TLC). A comparative analysis of green tea and black tea reveals significant differences in their chemical compositions and potential health benefits. Green tea boasts a higher phenolic content, ranging from 72.94 to 75.68 mg GAE/g, and exhibits greater antioxidant activity, with DPPH (2,2 -diphenyl - 1 -picrylhydrazyl) values between 91.29 to 96.55 ml Trolox/g, compared to black tea, which has phenolic content of 66.21 to 67.32 mg GAE/g and DPPH values of 79.84 to 87.73 ml Trolox/g. Conversely, black tea contains higher levels of caffeine (31.95 to 37.36 ppm), flavonoids (63.70 to 67.78 mg QE/g), and tannins (14.02 to 17.36 mg TAE/g) than green tea, which has caffeine levels of 25.18 to 28.41 ppm, flavonoid content of 27.17 to 37.80 mg QE/g, and tannin content of 5.87 to 7.21 mg TAE/g. The analysis indicates that black tea has higher concentrations of theaflavins, thearubigins, highly polymerized substances, and total liquor color compared to green tea, contributing to its distinctive flavor and appearance. While the moisture, ash, and lipid levels in both tea varieties are comparable, showing only minor differences, the research emphasizes the unique biochemical profiles of each type. Green tea is noted for its greater levels of polyphenols and antioxidants, which enhance its health benefits, whereas black tea is characterized by its higher caffeine content, making it a more stimulating beverage. These findings highlight the distinct qualities of green and black tea, suggesting that each may appeal to different consumer preferences and health needs.