The two approaches are valid. The choice depends on some factors:
Similarity - how much the canvas of each post is similar or not. This way, it can make sense to even mix the two approaches. For example, you can decide that the employee screens and the big Oss are very different and each have their own screen, while the bosses' screens are more similar and a single screen, with small differences solves.
Complexity - On the opposite side of the previous item, what is the complexity of each screen? What data sources does it have to load? What are the differences between each actor?
Scale - And tomorrow? How much can this system grow? Who will provide maintenance?
Usage - Each user will have access to a computer or they have to share the same?
Structure - Depends on the style of the developer. Some prefer few files with a lot of built-in functionality, while others prefer to spray code on several smaller files.
All these details should be weighed in choosing your approach.
Another question you raise is the identification of the position. It is assumed that being a business system, the user identifies himself when starting the use of the computer (login) and at this time, you would already direct the screen to this subject.
Otherwise, that is, use without identification, you have no choice but to show all options and restrict access according to the case.