ADSL2 is the successor to ADSL.
Rough notes for now. Differences include:
- Different modulation. ADSL2 uses a "16-state trellis filter and 1-bit QAM constellation" to improve datarates on high SNR links
- Variable length framing information, which can be used to reduce overhead in low-performance (<128kbit) connections
- Seamless power cutback. ADSl2 makes use of different power levels to reduce noise and crosstalk
- Line bonding for higher datarates
