A Professor is an academic  an academic rank at universities and other post-secondary education  institution
How are professors different from teachers at k-12?
Professor
Professor (commonly abbreviated as Prof.) is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, "professor" derives from Latin as a "person who professes" being usually an expert in arts or sciences, a teacher of the highest rank.
In most systems of academic ranks the word "Professor" only refers to the most senior academic position, sometimes informally known as "full professor". In some countries or institutions, the word "professor"
scientific teachers at vocational schools, technical colleges and further education colleges (', ', ') teaching at least till Bachelor's level and for Senior lecturers and Assistant professors at universities. Higher scientific teachers at Germany must hold facultas docendis in at least two different subjects.
Germany Form of address.
In Germany, a holder of the title/rank " (StR) is typically addressed by his title/rank followed by his other degrees in the same way as a holder of the title/rank of professor is