There's a Difference!
Although often thought to be synonymous with rebirth, this term is used - in Hinduism and Buddhism - to indicate a sort of controlled return to another life by human beings sufficiently advanced to master the bardo and to control time, place, and the parents connected with their approaching new birth.
Most schools of Tibetan Vajrayana have such people among their principal teachers who are thought to return over and over again in an unbroken line of incarnations. Probably the most famous of these are the Dalai Lama of the Gelugpa and the Karmapa, the Tai Situ and the Trungpa Tulku(s) of the Kagyudpa, but there are also several other lines that are also still continuing (see also Rimed).
Although often thought to be synonymous with reincarnation, there is a clear and important difference and distinction between these two concepts.
In both Hinduism and Buddhism, rebirth signifies a somewhat automatic return to a seemingly endless number of lives. Thus, the term applies only to the death and rebirth of an untrained, non-enlightened individual who has no control of his or her fate and future.