The different types of burning methods are:
CLV - Constant Linear Velocity (the burner starts burning at a speed, and burns at that speed the whole time)
CAV - Constant Angular Velocity (The burner begins the burn at a certain speed, and the speed increases at a steady rate until the burn is completed)
Z-CLV: Zonal Constant Linear Velocity (The burner burns steadily at a certain speed for a given amount of time, and then jumps to a faster speed at the beginning of the next "zone" I believe there are 3 "zones" on a CD)
P-CAV: Partial Constant Angular Velocity (The burner begins burning at a certain speed, but the speed accelerates quickly for a short time, then the acceleration slows down and is constant for the remaining time of the burn)
For more info on P-CAV and Z-CLV check out the article here: http://www.cdrinfo.com/Sections/Articles/Specific.asp?ArticleHeadline=PCAV+vs%2E+ZCLV+Recording+Technlogies&index=0
I tend to agree with Terminal Velocity that CLV and CAV are the best writing methods, however the point is easily debatable since a good quality burner using any method will still produce high quality burns.