T6 Aluminum, 6060 (6061 is a tad bit different) and 7075 are all different aluminum alloys. 6060 is the most commonly used in CNC mills. It is a billet aluminum, thus it is very strong, yet light weight. If you need me to explain the make up of them I will.
Graphite and Carbon fiber are definately similar, and a few RC companies are now using the more durable Carbon Kevlar.