From the tv series i watch, I've only heard "el profesor" or "la profesora" when talikng about high school teachers. What is the difference then between profesor and maestro?
In the United States, a teacher is used in grade schools and high schools. One must be more educated at the college or university level therefore world become a professor to teach at a higher learning level.
Profesor(a) is used for teachers of tendencially higher education. In Latin America typically a middle school teacher and higher, while in Spain it's used for high school and university teachers.