Principal engineer at Oracle, which is also called as tech lead, is a project leader who drives one project with a manager. A manager is usually charged with scheduling and resource distribution, while a tech lead decides technical part of a project. I loved that I can solely concentrate on technology without worrying about budget or administrative works. Oracle is really engineer-centric company. Each engineer can decide his/her work scope and many decisions are truely based on technology. Only downside I can think of is salary. It is not competitive with big companies such as Google or Facebook.