This article presents a comprehensive comparison between MXL (trapezoidal-tooth) and S2M (curvilinear-tooth) timing belts, focusing on their tooth profile geometry, meshing characteristics, transmission precision, load capacity, and service life. The trapezoidal tooth profile, first introduced by Uniroyal in 1964, suffers from significant stress concentration at the tooth root, leading to increased noise, vibration, and reduced load-carrying capacity at high speeds. In contrast, the curvilinear tooth profile (HTD, later STPD) was developed to mitigate the polygon effect and improve stress distribution. The MXL and S2M belts have similar pitches (2.032 mm vs. 2.000 mm) and are used in small-scale, low-power applications such as security surveillance equipment, printers, and financial devices. Through theoretical analysis and empirical testing using a PTZ camera’s preset positioning accuracy, the S2M timing belt consistently demonstrates superior transmission precision, longer service life, and better structural strength compared to the MXL belt, even under lower tension. Additionally, the S2M belt allows for narrower widths (e.g., 4 mm replacing 6.4 mm), potentially reducing system volume and cost. The article concludes by advocating for the promotion of curvilinear-tooth timing belts—especially in small-scale applications—to accelerate industrial upgrading and standard development in China.