dpollack,
The job title and description are all company dependent as can be seen by the various postings. Best bet, (assuming that they have them), is to check the job description where you work. For another example, where I work, we do not use the title "Lead Engineer". The technical Hierarchy goes as follows:
Associate Engineer
Engineer
Senior Engineer
Principal Engineer
Each has various pay grades and experience/educational requirements, Associate being an entry level type position, Engineer being one who works within area of discipline, Seniors have responsibilities for full products/processes and Principals are the company wide "experts" on various technologies, products, and processes. For a managerial "equivalency" the Seniors are equivalent to Group Managers and the Pricipals to Department Managers.
Regards