In this paper, a comparative study has been presented on Frequency-Coded Chipless RFID Tags with different bending styles and flexible substrates. The use of flexible substrates is essential in the development of wearable technologies. Flexible RFID tags are required to fit around the shape of an object. The RCS response characteristics of a tag must be the same when the tag is bent. However, the bending of a tag structure has an effect on the RCS response characteristics and increases the possibility of false identification. This study aims to understand the RCS response characteristics of flexible tags with different substrate and bending styles. For this study, two tags one with a circular ring-shaped slot and another with a square-shaped slot are used. When both tags were bent using the horizontal axis of the tag, the square-shaped tag exhibited less frequency change compared to the circular ring-based tag. Similarly, the tags were bent using the diagonal axis of the tag and observed the frequency change. Another comparison has been made using different flexible substrates. Kapton polymer material exhibits the least change in RCS characteristics for different bending styles while textile material exhibits the most change in RCS characteristics among the given flexible substrates.