In an orchestra, virtually no difference exists between a director and a music conductor. Since an orchestra does not typically have actors or dancers involved in the production, the need for differentiation does not exist. In the beginning, when the orchestra was being developed, the term musical conductor was used. However, contemporary conductors are more often referred to as musical directors. In the rare instance when additional non-orchestra performers are included in the orchestra, the director will be responsible for organizing the entire production.
In opera and theatre, there is a significant difference between a music conductor and a director. The conductor is responsible only for the music by conducting the orchestra and providing cues to the performers on stage. More often, the conductor will follow the performer and use his tempo since a performer can't generally see the conductor as the conductor stands below the stage. The director must organize the performers, the scene changes and deal with issues pertaining to subtitle placement and generally coordinate and control the overall artistic vision for the performance.
The wind symphony consists of a collection of brass, woodwind and percussion instruments. Sometimes, the ensemble will include keyboards, vocalists and assorted strings. Wind symphonies require that most of the members use some form of breath control to create sound. In this ensemble, either music director or music conductor may be appropriate. Most commonly, the director will be associated with the top band in a particular organization while a conductor will conduct one of the less elite ensembles. This setup most commonly exists within colleges and universities. However, the name conductor and director are usually used interchangeably within the wind symphony community.
In ballet, the director will be in charge of the entire show while the conductor has sole responsibility for the music. The director works directly with the choreographer, conductor, dancers and artistic director to ensure that the entire production comes together seamlessly. The director has the responsibility of ensuring that each member in the production knows his role, how to achieve it and how it relates to other roles.