Attanding a huge amount of performances I often experienced that ballets have thier own conductors. So what makes the difference(s) in conducting a ballet from an opera etc.? What are the specific point to be respected? Can anyone give me suggestions?

For many conductors, ballet is simply out of their zone of comfort. They don't have much experience watching ballet and don't feel they have any affinity for it. A few just don't like the idea that their musical insights might need to be subservient to choreographic interests and object to being asked to make slight tempo adjustments. There is a different level of responsibility handed to the conductor in ballet performances. Whereas in opera, the musicians in the pit can usually hear the singers and can determine whether the ensemble is working between the singers and the orchestra, in ballet the conductor is the only person involved who has any idea what is happening onstage. This places a heightened degree of responsibility on the conductor's shoulders. When reviews criticize the orchestra for poor ensemble with the choreography, they rarely seem to consider the fact that the players are completely in the dark and entirely dependent on the conductor. It's a special (and rare) talent.