Rocketman,
Fastcat02 and JEMMS are correct. I am in the machining business and I will tell you that the word "billet" is used (somtimes in my opinion) to get a higher price for the goods. Now I am not saying that billet is bad, quite the opposite, things machined from a solid chunk of aluminum are very nice. However certain parts that are not billet can be very good products as well. Manufacturing products from other processes (castings,fabrication, ETC..) perform just as well. Sorry I'll get off the soap box now.
Maxwell