Classification of these levels is grey at its best , still helpful . Advised to be not taken literally.
Beginner: Basic understanding of the simpler concepts and steps within tango; connection is possible but quite difficult to achieve.
Amateur : Aware of all the beginner concepts with a constant journey to gain confidence in executing all the beginners ideas.
Intermediate: Reasonable level of technical understanding of tango and a good repertoire of steps; connection is attained more readily, but still quite difficult to achieve consistently.
Advanced: Excellent understanding of the technical aspects of tango, technique, and at this level improvisation and connection are major factors.