At the time of creation of a new vendor staff profile, the vendor who creates the profile chooses an appropriate access level for them. The access level may be either full or limited.
Vendor staff users with full access will have exactly the same access permissions as the vendor themselves; they will be able to see and edit any data in the vendor account including vendor details, staff and financial info. Vendor staff without full access will be able to access the products, shipping settings, orders and commissons of the vendor, but they will not have access to vendor details, staff and financial info.
Here is the user interface view of a vendor staff member with full access:
And here is the user interface view of a vendor staff member with limited access: