SDSL (Symmetric Digital Subscriber Line) and ADSL (Asymmetric Digital Subscriber Line) are both types of DSL technologies used for high-speed internet over copper telephone lines. SDSL provides equal upload and download speeds, making it suitable for businesses that require balanced data transfer rates for activities such as video conferencing and file sharing.

In contrast, ADSL offers higher download speeds compared to upload speeds, catering to typical residential users who prioritize faster download performance for activities like streaming and browsing while having lower upload needs. However both SDSL and ADSL are currently being decommissioned by carriers