private vs. fileprivate on global declaration in Swift3?

Using Swift
1

Should I use private or fileprivate to declare global variables/consts in Swift 3? e.g.

fileprivate let a = 1
fileprivate class SomeClass {
    fileprivate b = 0
}

or

private let a = 1
private class SomeClass {
    private b = 0
}

Thanks!

If they are identity, then I think the Swift team should tell us which is better.