Splitting the app into different codebases or databases will complicate development, and the speed at which you're able to iterate. Ultimately, you will want to

Splitting the app into different codebases or databases will complicate development, and the speed at which you're able to iterate. Ultimately, you will want to be presenting the same data in different ways for the different roles (managers and employees). A single app where features and UI depend on a user's role or credentials will be easier to develop and reason about.