The immediate observable difference between HomePlugAV and HomePlugAV2 is the marketing of gigabit-class speeds. To clarify though, the gigabit speed is at the PHY layer which really just means you get gigabit connectivity, not gigabit throughput. Other key advances include:
- Increased bandwidth through use of higher band spectrum
- Inherent repeater functionality
- Power save mode
Underneath these advancements, the core mechanisms such as the PHY, MAC, and Central Coordinator remain the same.
Having almost three times the band in which to operate allows for multiple HD streams and more bandwidth-intensive usage. HomePlug AV2 also utilizes beamforming, which is what allows for better transmission channel adjustments such as OFDM. In addition, MIMO enables the Powerline adapter to use any two wires in a three-prong outlet for transmission, whereas HomePlug AV always uses the line-neutral pair. Extended coverage is also more likely without having to purchase an extra Powerline adapter since each AV2 node has inherent repeater functionality.
From an efficiency perspective, Powerline adapters built according to the HomePlug AV2 specification have a sleep mode to prevent unneeded power draw. Until activated to transmit data, a Powerline adapter enters a sleep state with specified times to awake to check for any data transmission requests. The HomePlug AV2 logo has been revised, so you won't be able to tell just by the logo whether the Powerline adapter you're purchasing maps to that specification. Be sure to look at the specs listed on the side or back of the box for verification!