The A330s are quieter for a couple of reasons. The engines are located further out on the wing, and Airbus puts more soundproofing into their cabins. This is a Boeing thing which goes back to the cabin sound studies when they were developing the 707.

As for age, the 764s were delivered between 2000 and 2002. The A330s between 2003 and 2006. On average, the A330s are 4 years newer than the 767s, but the 767s have had interior refurbishments in that period (Y AVOD, J Flat Beds). I think the A330s shipped with AVOD.