How do "lecturers" differ from "professors" in large universities?
I notice that some universities have academic positions known as lecturers. Are these positions different from professors? Are transitions from instructors to the professor track relatively easy. This position seems similar to the adjunct professor position.
Note that I am talking about universities in the USA.
I used to be a lecturer at a university in the southwest USA. As a lecturer, I was charged with only teaching lower division undergraduate courses (freshman & sophomore level). In general, research and service is not a requirement for lecturers (unlike professors), but we are required to teach a larger load than professors. And we were generally yearly appointments with no chance of tenure.
A lecturer is effectively a contractor who happens to be a university employee rather than working for another company. A lecturer position may also be part-time, and can sometimes be called an "adjunct" position.
@Suresh: I think it means that you are employed as needed for a period of time, but are not guaranteed employment year to year.
Note: Some universities have a career lecturer/teaching professor track. At such universities, you can be promoted to "senior lecturer", and although this doesn't come with tenure, it switches over to something more like a 5 year contract instead of a 1 year contract, and the intent is to allow people to stay at the university long term.
@aeismail, it depends. There are universities that have lecturers with the equivalent of tenure (they may call it something else, like "security of employment", but it is functionally equivalent). So, I agree with all of Paul's answer, except for the last sentence -- in practice there is considerable variation from university to university on the specifics of how lecturers are hired or retained, and what degree of job security they enjoy.
@Suresh: Regarding Paul's comment, it should be noted that in the US, this is the norm for employees in all sectors: employment is generally "at will" and university professors are among the very few employees, in any industry, who have any sort of guaranteed job security.
Where I work (Canada) a Lecturer gets promoted to Senior Lecturer and then has bit more job security. We can/are teaching all years (1-4, which in US is freshman all the way to senior). Unlike Professors, we don't have graduate students, have a higher teaching load, are expected to have the same service load as the professors and don't have to do research (which is a big one).
In many places in the US, thinking of research-oriented universities, "lecturer" or "instructor" is not at all like assistant, associate, or full prof, and is not tenure track. "Lecturer" and "instructor" are closer to "adjunct", and are teaching-oriented. Sometimes the positions are effectively long term, but most often just year-by-year, or even term-by-term. Any transition from these positions to tenure track would be unusual, although in the more recent economic upheaval, sometimes people take such positions just to be employed for a year, waiting out the job market.
I agree with most of this answer, though in my experience lecturers are usually pretty different from adjuncts (lecturers are often full-time employees, adjuncts are typically part-time and in some ways may be more like contractors than employees).
I can give the Australian context.
"Lecturer" is a rank in Australia. The typical hierarchy is "Associate Lecturer", "Lecturer", "Senior Lecturer", "Associate Professor", "Professor" (see this discussion). Thus, on the academic ranking scale from A to E, lecturer is B.
However, it is also common for anyone who gives lectures in a university to describe their job in terms of "being a lecturer". In this sense "lecturer" is an often informal job title that may be used by an academic at any academic rank. For example, someone might ask you what you do for a living and you might answer "I'm a lecturer at a university". Such a response could be given by someone at any academic rank.
Agreeing with the other answers, "Lecturer" is often the title given to full-time non-tenure track (i.e. contractual) faculty who typically only have instructional duties. Depending on the style of the institution, it may or may not be possible to move into the tenure-track. Lecturer, however, is not always a "dead-end". Some schools have a separate promotion system to reward and promote their non-tenure track faculty (similar to the way you would reward and promote staff). At these institutions there might be ranks, like Lecturer I, Lecturer II, Senior Lecturer, etc.
Disagreeing with the other answers, the term "adjunct" usually refers to a part-time instructor. Adjuncts usually have few if any opportunities for advancement. At many institutions, adjuncts may be distinct from Lectures (as a Lecturer is a full time appointment). My institution confusingly calls full-time and part-time instructors "Lecturer", but then proceeds to treat them as very different types of employee.
The terminology of positions differ from country to country. Lecturer has its origins in the British system. I know that when positions in other (non-English speaking) countries are announced internationally they may use this terminology. This is of course because each language have their own words for different positions. There is no straight translation between these systems including the system used in for example the US consisting of Assistant, Associate and Full Professors. The form of the employment also varies from country to country for historical reasons. A Lecturer is probably similar to an Assitant Professor, whether it is a permanent position or not probably varies.
I am teaching in University (Mongolia). In our country calling every person who is teaching in university, first "Lecturer". We are starting from assistant lecturer, lecturer, senior lecturer going on. If you have PhD degree you can go to next level: Associate Professor and Professor. But in generally all calling like lecturer. If you are already in Professor position your teaching hours is reducing and increasing hours for research and projects. Different between Lecturers and Professors in our meaning sounding like, have academic degree or not. But not every body can become Professor who have PhD degree. You have to be lead some main research direction or field, you have to write books about your field. Big difference from European countries Professor position in our university is not lifelong. After every 3 years you have to be accredited. If you are enough good by this process you can keep your position, if not your level is reducing. I am agree that Professor have to concentrate more to research and Lecturers can be focused for teaching.
I'm a staff member at an American university. Lecturers here don't take on graduate students (Research Assistants) to advise for their thesis, guiding their research, etc. which is a major component of a professor's duties and legacy.
This question has been really interesting to follow. Clearly there is a huge breadth of definitions for lecturer positions. I am a full-time lecturer and my responsibilities are to teach graduate level courses. A significant portion of my responsibilities also includes admission decisions and advising masters students including their MA theses, projects, and research. No tenure track, but the trend here is a more long-term career / relation with the institution. Non-faculty, but with many faculty duties. Even within a particular institution, there can be some variations.