American "professor" is merely instructor, lecturer or teacher in the rest of the world, particularly in countries where British English predominates. Professor is a senior title given to lecturers upon promotion after years of work. Referring to all lecturers as "professor" is an Americanism.
If you look at college catalogues from the United States you will see job titles of "Professor, Assistant Professor, Associate Professor, Lecturer", and ever "Instructor". Where I went to school, college teachers with a PhD were addressed as Doctor while those without a doctorate were addressed as Mr. or Mrs., and a couple preferred to be addressed by their first names. I personally can't remember anybody at my schools being addressed as "Professor", but I hear that a lot on movies and TV shows, probably to indicate that the character teaches at the college level. Everyone who teaches anything is a teacher, we just say "Elementary School teacher" and High School teacher" instead of "Elementary School Professor" and "High School Professor", regardless of the degree they hold. We also tend to pair "College" with "professor" instead of "College" with "teacher". It might just be style or a speech tradition, but it is so.
Whatever differences there may or may not be between British and American English, it still remains that "teacher" and "professor" are two different words in both English and Arabic.