Hiya,
Section Access is what's usually referred to where you have a user / group connected to specefic data / data ranges with the use of Section Access.
The Section Access (the Access part) is where you build your security (Username, Security Group (USER, ADMIN), etc.).
The Section Application is a statement that preceeds your data load (with a field that connects to your data) and the link determines what a user can / cannot see.
