What are the differences between if and switch operator?

They are both control flow statements.

Perhaps this will help:

let testValue = true

You will notice that testValue is a Bool assigned to true.

But what if you want to build logic on that? Traditional if / else statements might look like this:

if testValue {
    // Do something for testValue is true
} else {
    // Do something for testValue is false
}

Where a switch statement can be written like so:

switch testValue {
    case true:
        // Do something
    case false:
        // Do something
}

Really it is a matter of style, and logic. If you are testing for one condition, then a simple if / else statement might work. Otherwise, switch statements give you power to concisely and clearly express your intentions for a number of scenarios. This becomes very evident in a long if / else statement like:

if someValue {
    // Do something
} else if someOtherCondition {
    // Do something
} else {
   // Do another thing
}

There are of course more advanced things you can do with switch statements as well, and coupled with Enums are quite powerful. I would recommend checking out the Apple Swift E-Book under the chapter on control statements for a further look at the switch statement.

Hope this helps!

Cheers!