Which traditions have gurus? On the site I often read posts referencing gurus. My Buddhist group (Triratna) doesn't really have a concept of gurus - certainly no-one uses the term. Which traditions have gurus? I most associate it with Tibetan Buddhism but I could be wrong in that. Also is there an difference between a Buddhist teacher and a guru or are they really just the same thing?
Not only in Tibetan Buddhism, they also have gurus in Zen Buddhism but there they are addressed as masters (sifu, sensei, sabunim etc). What counts is not a name but the personal relationship of mentorship.

I suppose "mentor" would be a better term than "teacher". Other options I like include "preceptor" and "benefactor". As was explained to me by one of my spiritual guides, a Chinese practitioner of Vajrayana, the word "teacher" emphasizes transfer of information, while "guru" stresses the upbringing / personal transformation aspect.

In Tibetan schools, esp. in Vajrayana they go as far as to say that the faith in one's guru is single most important factor of Enlightenment, and make guru-yoga, practice of deliberate worship of one's guru, the foundation of all other practices. 

The official term preferred by Tibetan texts is "kalyanamitra", spiritual friend. This is supposed to make it sound a little more democratic than the overly patriarchal "guru", although in practice the relationship is rarely as personal as a real friendship.

There is a nice Wikipedia article on Kalyāṇa-mittatā, which mentions an early occurrence of this special interpretation of spiritual friendship in Visuddhimagga.

Here is also a Pali Canon quote that defines spiritual counseling (DN 31):


  The mentor (atthakkhayi, "the shower of the goal") is known by four things to be a goodhearted friend (suhada mitta):  
  
  
  he restrains you from wrongdoing,  
  he guides you towards doing good,  
  he lets you know what you did not know before,  
  he points out the path to heaven.  
  


So I suppose personal mentorship is not just a Mahayana thing if it can be traced back to Pali Canon.