Avast Vs AVG FREE antivirus software

Foe light Weight Anti Virus Software ,what is the difference between Avast and AVG?Which is better?

As you might know.Live scan is important in fighting against viruses .Avast offering the live scan, but then AVG has a better interface.In fact AVG is good just like Avast. AVG not resource hungry. You can run a manual scan every night even it doesn't have a live scam features.Both are good good light weight anti virus software for people who have a slow computer or laptop.And Both has free version for download.