A possible scenario where user permissions can be of use is when a business is selling at both retail and wholesale prices. That's a typical evolution of a company as it grows - to expand into B2C apart from B2B (or vice versa) - and that can be supported in Megaventory as well.
In this scenario, if your customer is an individual or a company entity, a different price list should load when you create a sales order. On top of that, you may have different people to manage B2C and B2B sales.
So in Megaventory, you can create two different types of invoices - one for retail and one for wholesale. Following that, you can grant access to both of them to a user that handles wholesale purchases and sales. Alternatively, you can choose to limit a user so that they can do either and not both.
In the above image, the user has access to both types of invoices. In a different example where they have access to one of them only, the drop-down menu would show just one option.
To grant different access levels to a user, click on your Profile Icon and select Company & Billing (Admin). From the menu on the left, click on Users and then click on Edit User Permissions, next to the user you want to edit their access rights.