Band directors are individuals who conduct a band. A band director usually is the one that stands in front of a band at a concert, or one who teaches. A band director is also one that would make sure that the band is in tempo. In marching Band the directors are the Drum Majors.
There is a common misunderstanding between the terms "director" and "conductor" which must not be confused. A conductor is primarily in charge of conducting an ensemble. The group's performance is actively being led by the conductor. A director should have no direct control over a performance. A direct is in charge of overseeing the entire group's administration. A marching band director does not necessarily conduct the band, although he could. A jazz band director will lead the group by starting a piece or acknowledging soloists, but he does not conduct.