What is the difference between these two? Any ideas or is there a difference?

What is the difference between these two? Any ideas or is there a difference?

I have XM and enjoy it, no commercials and I paid like $75 for an entire year. I know Howard Stern is on Sirus.:eek:

I've been to a couple car audio shops and have asked the same question. XM radio is much better, Sirus apparently doesn't get the vote!