What Is Difference Between Sirius Sportster 4 And 5 What Is The Difference Between A Sirius Radio Sportster 4 And Sportster 5. Is It Worth Paying More For The 5 .

What is the difference between a Sirius radio sportster 4 and sportster 5. Is it worth paying more for the 5 . - what is difference between sirius sportster 4 and 5

I know nothing about these radios. My wife bought the Sportster 5 on Father's Day, I found the 4 is much less expensive, but the same functions. Also involved is how the installation?