The first point you made about the difference in social status and language register is the most accurate. Conversations between friends generally involve a more informal tone, using slang and colloquialisms, as they share a sense of equality in status. In contrast, conversations between a boss and an employee are typically more formal, adhering to standards of professionalism, with proper grammar and a limited use of slang.
The second point about topic focus has some merit as well. Friends often discuss personal topics, while boss-employee conversations focus more on work-related matters. However, it’s not entirely true that bosses and employees never share personal information; this can vary by workplace culture.
The third point about intonation and Non-Verbal Signals (NMS) is somewhat accurate, as friends may exhibit more varied intonation and expressiveness, while professional interactions may lean toward a more restrained style, though this can also vary significantly based on the individuals involved.
The fourth point on conversation duration can also be quite variable. Conversations can be short for efficiency in a work setting; however, important discussions may be longer.
In summary, the key differences lie primarily in the formality of language, social dynamics, and the subjects of discussion.