Mommy/Babyboy is usually a dom/sub dynamic that has “Mommy” as the dominant and “Babyboy” as the submissive. This play can include age regression (ie, pretendin to be a small child) but not always.
Master/slave refers to a dom/sub dynamic where the “Master” is the dominant and the “slave” is the submissive. Usually, an M/S dynamic involves service to the dominant and full submission by the slave as if the Master “owned” the slave and the slave would do anything the Master commanded.
Teacher/student refers to role play where the dominant or top plays the role of teacher and the sub/bottom plays the role of student. The teacher can command the student to do homework, etc and get punished.
Boss/secretary refers to role play where the dominant or top plays the role of “boss” who can then tell the “secretary” what to do.